Electric axial flux machine, an electric axle drive train

Abstract

The invention relates to an electric axial flux machine (1), in particular for a drive train (2) of a hybrid or fully electrically operated motor vehicle (3), the axial flux machine (1) comprising: a stator (4) having a first annular disc-shaped stator body (5); and a rotor (7) arranged axially at a distance from said stator. The axial flux machine (1) also has a rotor position sensor (8) which comprises a sensor target (9) and by means of which the position of the rotor (7) relative to the stator (4) can be determined, the rotor position sensor (8) with the sensor target (9) being positioned radially inside the first annular disc-shaped stator body (5) with at least one overlap region (10), that is axial in sections, with the first stator body (5) inside the axial flux machine (1).

Description

[0001] Electric axial flux machine and electric axle drive train

[0002] The present invention relates to an electric axial flux machine, in particular for a drive train of a hybrid or fully electric motor vehicle. The axial flux machine comprises a stator with a first annular disk-shaped stator body and a rotor axially spaced therefrom. The axial flux machine further comprises a rotor position sensor with a sensor target, by means of which the position of the rotor relative to the stator can be determined. The invention further relates to an electric axle drive train.

[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 electric motors, the relative positioning of the parts through which the magnetic field flows is crucial. This applies both to the mechanical structure of the electric motor, which holds the parts and positions them precisely, and to precise knowledge of the angular position of the rotating parts. A precise, rigid mechanical structure is important, as even small positional deviations between the parts can significantly influence the magnetic flux (e.g., due to changes in the air gap). However, precise knowledge of the current position of the rotor is also crucial, as the constantly changing position of the magnets integrated into the rotating rotor (angular position) relative to the magnet integrated into the stator must always be precisely known in order to control the electric motor correctly.The changing angular position of the rotor must be precisely known at all times in order to determine the alignment of the rotor components (e.g. the rotor magnets, which are usually designed as permanent magnets) relative to the stator components (e.g. the stator magnets, which are usually designed as electromagnets) and to be able to coordinate the motor control accordingly. It is therefore important to integrate a rotor position sensor into the mechanical structure of the electric motor in such a way that the sensor can detect the relative position of the magnetically relevant parts precisely, i.e. with the smallest possible tolerance influence. At the same time, the sensor must not have a negative impact on the mechanical structure of the electric motor due to its size and installation conditions, so that a sufficiently robust and dimensionally accurate design of all parts and assemblies is possible, as well as their precise alignment during assembly.

[0006] Especially in electric motors for vehicle applications, the rotor position sensor must be integrated into the structure of the motor as compactly and cost-effectively as possible.

[0007] In an axial flux motor, axially directed magnetic fields act primarily between the disc-shaped rotor and stator assemblies, separated only by narrow air gaps, generating a torque that drives the rotor. The disc-shaped design of the rotors and stators allows for air gaps extending far outward radially between these components, allowing the magnetic fields to act across large diameters, resulting in efficient torque buildup. Due to its disc-shaped main assemblies, axial flux motors are particularly well-suited for applications where a very short electric motor length is essential and a relatively large motor diameter is still acceptable.When developing axial flux motors, it is therefore very sensible to aim for the shortest possible design so that the theoretical advantage of the axial flux motor relative to the radial flux motor is maintained and at the same time to ensure that the outer diameter of the motor is not larger than absolutely necessary.

[0008] The rotor position sensor should therefore be integrated into the axial flux motor in such a way that it does not significantly increase the motor dimensions, either axially or radially. Furthermore, the rotor position sensor must be positioned so that it is operatively connected to both the rotating rotor and the stationary stator in order to detect the angular position of the rotor relative to the stator. Therefore, the object of the invention is to provide an axial flux motor with a rotor position sensor with a design that is as compact as possible, both axially and radially. Furthermore, the object of the invention is to realize a correspondingly compact electric axle drive train.

[0009] This object is achieved by an electric axial flux machine, in particular for a drive train of a hybrid or fully electric motor vehicle, wherein the axial flux machine has a stator with a first annular disk-shaped stator body and a rotor axially spaced therefrom, and the axial flux machine further has a rotor position sensor with a sensor target, by means of which the position of the rotor relative to the stator can be determined, wherein the rotor position sensor with the sensor target is positioned radially inside the first annular disk-shaped stator body with at least one sectionally axial overlap area with the first stator body within the axial flux machine.

[0010] This provides the advantage of allowing the axial flux machine to be designed with a particularly short axial length. The particularly advantageous arrangement and design variants described in more detail below also enable a simple and reliable connection of the sensor target to the rotor and the rotor position sensor to the stator, thus enabling particularly high measurement accuracy. Due to the sufficiently large distance from the motor components through which the magnetic fields that generate the motor torque flow, the rotor position sensor is protected radially within the rotor shaft and / or a rotor bearing from high temperatures and / or strong magnetic or electric fields.

[0011] In addition, the particularly advantageous arrangement and design variants described in more detail below allow the rotor position sensor to be accessible from the side or front even when the axial flux machine is fully assembled. This allows the rotor position sensor to be installed very late in the axial flux machine assembly process, which reduces the risk of damage during motor assembly and also facilitates subsequent repair or replacement of the rotor position sensor.

[0012] The magnetic flux in an electric axial flux machine (AFM), such as an electric drive machine of a motor vehicle designed as an axial flux machine, is directed axially to a direction of rotation of the rotor of the axial flux machine in the air gap between stator and rotor.

[0013] 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 F-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 I-arrangement.

[0014] In principle, it is also possible for a plurality of I-type and / or H-type rotor-stator configurations to be arranged axially adjacent to one another. In this context, it would also be possible to arrange several I-type rotor-stator configurations axially adjacent to one another. 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 multiple rotor shafts.

[0015] 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 designed as a single piece or segmented in the circumferential direction. The stator body can be formed from a stator lamination stack with a plurality of laminated electrical steel layers. Alternatively, the stator body can also be formed from a pressed soft magnetic material, such as the so-called SMC material (Soft Magnetic Compound). The rotor of an electric axial flux machine can be designed, at least in part, as a laminated rotor. A laminated rotor is designed with layers in the radial direction. Alternatively, the rotor of an axial flux machine can also have a rotor carrier, which is correspondingly equipped with magnetic sheets and / or SMC material and with magnetic elements designed as permanent magnets.Preferably, the rotor does not contain any other magnetically conductive materials besides the permanent magnets. In particular, the permanent magnets can also be incorporated into a rotor formed entirely or partially from a plastic.

[0016] A rotor shaft is a rotatably mounted shaft of an electrical machine to which the rotor or rotor body is non-rotatably coupled.

[0017] 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.

[0018] A control device preferably has a wired or wireless signal input for receiving electrical signals, such as sensor signals. Furthermore, a control device preferably also has a wired or wireless signal output for transmitting electrical signals, in particular.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] The electric axial flux machine can preferably also 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.

[0027] The electric axial flux machine can particularly preferably also be provided for use in a hybrid module. In a hybrid module, components and functional elements of a hybridized drive train can be spatially and / or structurally combined and preconfigured, so that a hybrid module can be integrated into a motor vehicle's drive train in a particularly simple manner. In particular, an axial flux machine and a clutch system, in particular with a separating clutch for coupling the axial flux machine into and / or disengaging the axial flux machine from the drive train, can be present in a hybrid module.

[0028] The sensor housing serves to secure the active components of the rotor position sensor relative to one another. For this purpose, the sensor housing can also be plate-shaped. However, the sensor housing is preferably designed to enclose the active components of the rotor position sensor partially or completely. The sensor housing can be constructed in one piece or in multiple pieces. Most preferably, the sensor housing is pot-shaped with a plate-like closure element. Furthermore, the sensor housing is preferably made of a plastic.

[0029] 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.

[0030] According to an advantageous embodiment of the invention, the rotor can be provided, at least in sections, with a rotor shaft configured as a hollow shaft, and the sensor target can be arranged in the hollow shaft, which allows for a particularly compact axial design of the axial flux machine. In this context, it is also conceivable for the rotor shaft to be configured as a hollow shaft in sections, in which the rotor shaft has a concentric blind hole.

[0031] According to a further preferred development of the invention, it can also be provided that the rotor position sensor engages axially at least partially, preferably completely, into the hollow shaft, which also contributes to a particularly compact axial design of the axial flux machine. Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the rotor shaft is mounted relative to the first stator body via a first rolling bearing and relative to the second stator body via a second rolling bearing, wherein the rotor position sensor with the sensor target is arranged radially within the first rolling bearing, which contributes to a radially and axially compact design.

[0032] According to a further particularly preferred embodiment of the invention, it can be provided that the rotor position sensor and / or the sensor target have / has an axial overlap region with the first rolling bearing, which also enables an axially as well as radially particularly compact design of an axial flux machine.

[0033] Furthermore, the invention can also be further developed such that the rotor position sensor has a substantially cylindrical sensor housing, which is arranged radially at least partially within the annular disk-shaped stator body and axially protrudes at least partially into the first annular disk-shaped stator body. The advantage of this embodiment is that the rotor position sensor can be provided preconfigured in the sensor housing, which significantly simplifies its assembly.

[0034] In a likewise preferred embodiment of the invention, it can also be provided that the axial flux machine is accommodated in a motor housing, wherein the motor housing has a housing section extending in a radial plane, to which the sensor housing is attached. This allows a structurally particularly rigid connection between the motor housing and thus also the stator to be achieved, resulting in correspondingly good measurement accuracy of the rotor position sensor.

[0035] It may also be advantageous to further develop the invention such that the rotor position sensor has at least one electrical cable that extends radially outward over the housing section. The advantage of this is that the cables are easily accessible during assembly. The rotor position sensor is preferably connected to a control unit of the axial flux machine via the cables.

[0036] The configuration variants of an axial flux machine described here are not only applicable to electric axle drive trains. The solutions presented can also be used for axial flux machines that are located, for example, at other locations in a motor vehicle.

[0037] The object of the invention can also be achieved by an electric axle drive train comprising a first axial flux machine according to one of claims 1-8 and a second axial flux machine according to one of claims 1-8. This makes it possible for each vehicle wheel of a vehicle axle to be driven separately by an axial flux machine. Such axle drive train concepts are also referred to as twin-axle or dual-drive.

[0038] Finally, the invention can also be advantageously designed such that the rotor position sensor of the first axial flux machine and the rotor position sensor of the second axial flux machine are located directly opposite each other in the electric axle drive train, whereby in particular an advantageous cable routing between the axial flux machines can be realized.

[0039] The invention will be explained in more detail below with reference to figures without limiting the general inventive concept.

[0040] It shows:

[0041] Figure 1 shows a first embodiment of an axial flow machine in an axial section,

[0042] Figure 2 shows a first embodiment of an axial flow machine in a perspective partial sectional view, Figure 3 shows two rotor position sensors arranged next to one another in a perspective view,

[0043] Figure 4 shows a second embodiment of an axial flow machine in an axial section,

[0044] Figure 5 shows an electric axle drive train of a motor vehicle with two axial flux machines in a schematic block diagram.

[0045] Figure 1 shows an axial flux machine, such as those used in electric axle drive trains of motor vehicles. The axial flux machine 1 has a rotor 7 and a stator 4.

[0046] The stator 4 consists of two bodies 5, 6 which are connected to one another radially on the outside and which are each rotationally decoupled from the rotor shaft 11 via a bearing point on the radial inside. The rotor 7 is fastened to the rotor shaft 11 and consists of a disk-shaped section which extends radially outwards between the two stator bodies 5, 6. This corresponds to an axial flux machine 1 in an I arrangement. Between the two stator bodies 5, 6 and the rotor 7 are the air gaps through which the axial magnetic flux of the axial flux machine 1 flows. In the axial flux machine 1 shown in half section in Figure 1, the rotor 7 is equipped with permanent magnets and the stator 4 with electromagnets. The magnetic spring of the axial flux machine 1 can generate a torque which acts on the rotor 7 and is transmitted from there to the rotor shaft 11.The rotor shaft 11 protrudes axially from the axial flux machine on one side, thus forming the transmission element through which the torque of the axial flux machine 1 can be transmitted to an adjacent component. This adjacent component can be, for example, a transmission, a differential, a shaft, or a wheel of the motor vehicle. The rolling bearings 13, 14 between the stator bodies 5, 6 and the rotor shaft 11 connect the rotor 7 to the stator 4 in a rotationally decoupled manner.Figure 1 shows an electric axial flux machine 1, in particular for a drive train 2 of a hybrid or fully electric motor vehicle 3, wherein the axial flux machine 1 is configured in an I-design, in which the stator 4 has a first annular disk-shaped stator body 5 and a second annular disk-shaped stator body 6 axially spaced therefrom, and the rotor 7 is arranged axially between the first stator body 5 and the second stator body 6. The axial flux machine 1 further has a rotor position sensor 8 with a sensor target 9, by means of which the position of the rotor 7 relative to the stator 4 can be determined.

[0047] In order to detect the position of the rotor 7 relative to the stator 4, a rotor position sensor 8 is integrated into the axial flux machine 1. The rotor position sensor 8 is positioned with the sensor target 9 radially within the first annular disk-shaped stator body 5 with at least one sectionally axial overlap area 10 with the first stator body 5 within the axial flux machine 1.

[0048] The rotor position sensor 8 is therefore located largely radially within the rotor shaft 11, which is designed as a hollow shaft 12 in this area. The rotor position sensor 8 consists of an active and a passive part. The active part of the rotor position sensor 8, which is connected to the stator 4, contains the electrical or electronic components of the rotor position sensor 8 and is connected to a control unit of the axial flux machine 1. The passive part of the rotor position sensor 8 represents the sensor target 9, whose angular position can be detected by the active part of the rotor position sensor 8.

[0049] In this embodiment shown, the sensor target 9 is formed by a disk provided with a plurality of recesses distributed around the circumference, which is connected to the hollow shaft 12. The active rotor position sensor 8 fastened to the stator 4 detects the contour of the sensor target 9 which is interrupted around the circumference. Since the number, circumferential extent and circumferential position of the wing-like extensions of the passive sensor target 9 are coordinated with the magnets in the rotor 7 (e.g. permanent magnets) and there is a fixed connection between the rotor magnets and the wing-like extensions of the passive sensor target 9 via the rotor shaft 11, which keeps the installation position relative to one another constant even during operation of the axial flux machine 1, the circumferential position of the rotor magnets relative to the stator 4 can be determined from the measurement signals of the active rotor position sensor 8, which reacts to the position of the extensions and recesses of the passive sensor target 9.Alternatively, the passive sensor target 9 can also be formed directly by the rotor shaft 11, for example, by the shaft contour having elevations and depressions in front of the active rotor position sensor 8, which are arranged in a manner similar to the wing-like extensions described above. Alternatively, the rotor position sensor 8 can also detect the position of regions with better electrical or magnetic conductivity and regions with poor electrical or magnetic conductivity, or detect the position of stronger magnetic regions and weaker magnetic regions.

[0050] The rotor position sensor 8, which contains the electronic components, is attached to the motor housing 17 of the first stator body 5 via a sensor housing 16. The sensor housing 16 is inserted into the central opening of the housing section 18 of the motor housing 17, which extends in a radial plane, and is screwed thereto. The sensor housing 16 closes the central opening of the housing section 18 and is located a short distance axially in front of the annular end face of the axial end region of the rotor shaft 11 facing the rotor position sensor 8. Radially within the rotor shaft 11, which is at least partially formed into a hollow shaft 12, the active rotor position sensor 8 is attached to or in the sensor housing 16 in an axially projecting manner, and thus protrudes into the hollow shaft 12. The passive sensor target 9 is located axially in front of the active rotor position sensor 8 at a short axial distance.In this embodiment, the passive sensor target 9 is pressed into the hollow shaft 12 with its annular fastening area. The wing-like extensions protrude radially inward from the annular fastening area. To make the axial position of the passive sensor target 9 as easy as possible, an adjusting ring 22 is located between the annular fastening area of ​​the passive sensor target 9 and the shaft shoulder 21, which serves as an axial stop during the pressing-in process. By selecting an adjusting ring 22 with an appropriate axial thickness, it is easy to ensure that the passive sensor target 9 is pressed into the correct axial position.

[0051] The rotor 7 thus has a rotor shaft 11 designed as a hollow shaft 12, in which the sensor target 9 is arranged. The rotor position sensor 8 engages axially at least partially, preferably completely, in the hollow shaft 12. The axial flux machine 1 is accommodated in a motor housing 17, wherein the motor housing 17 has a housing section 18 extending in a radial plane, to which the sensor housing 16 of the rotor position sensor 8 is attached.

[0052] Alternatively, the sensor housing 16 can be partially or completely formed as a single piece from the housing section 18 of the motor housing 17. The housing section 18 is then drawn radially inward, for example, to such an extent that it can directly fix the active part of the rotor position sensor 8. A separate sensor housing 16 would then no longer be necessary.

[0053] The embodiment illustrated in Figures 1-2 shows a particularly compact and space-saving arrangement of the rotor position sensor 8. The rotor position sensor 8 is located not only radially within the rotor shaft 11, but also radially within the rolling bearing 13 acting as the rotor bearing, and radially within the motor components through which the magnetic fields that generate the motor torque flow, which in the case shown is in particular the first stator body 5. The rotor position sensor 8 is also located axially in a region in which axial sections of the rotor shaft 11, the rolling bearing 13, and the motor components through which the magnetic fields that generate the motor torque flow, namely the first stator body 5, are also arranged.Each of these features would already contribute to a compact motor design; in the combination shown here, the rotor position sensor 8 can be integrated into the axial flux machine 1 in a substantially space-neutral manner and contributes to the axial flux machine 1 being designed to be very short axially.

[0054] The active rotor position sensor 8 is fastened to the housing section 18 of the motor housing 17, which is designed as a front side wall, by axially thickening the housing section 18 radially inside the motor components through which the magnetic fields causing the motor torque flow, and by this thickening having the axial threaded holes 23 for fastening the sensor housing 16 and the bearing seat for the outer ring of the rolling bearing 13.

[0055] Radially within the thickened portion, the housing section 18 merges into a short, radially inward-facing web, which serves axially as a contact surface for the rolling bearing 13 and has a center seat for the sensor housing 16 of the rotor position sensor 8 radially on the inside. Adjustment rings (not shown) between the housing section 18 and the rolling bearing 13 may also be useful at this point. A cylindrical outer surface of the sensor housing 16 is inserted into this center seat. In addition, next to the center seat, a part of the sensor housing 16 projects radially outwards past the housing section 18 of the motor housing 17 and is screwed there to the housing section 18. In the exemplary embodiment shown in Figures 1-2, this area of ​​the sensor housing 16 is formed by three fastening tabs 25 distributed around the circumference, which can be clearly seen in Figure 2.Between the three mounting tabs 25, there is space for the electrical lines 19, designed as cables, which connect the active part of the rotor position sensor 8 to the control unit (not shown) of the axial flux machine 1. Additionally, the space can also be used to accommodate other parts or components that must be arranged in the immediate vicinity of the axial flux machine 1.

[0056] Radially within the center seat, the sensor housing 16 extends axially inwardly in front of the rolling bearing 13 and axially in front of the end of the rotor shaft 11, which forms the bearing seat for the inner ring of the rolling bearing 13. Within the shaft end, which is designed as a hollow shaft 12 at least in the area of ​​the rotor position sensor 8, the active part of the rotor position sensor 8 is connected to the sensor housing 16. The electronic components of the active rotor position sensor 8 are attached to or in the sensor housing 16.

[0057] Figure 1 shows the axial flux machine 1 installed in a drive train housing 26. This motor arrangement is intended for an electric axle drive train 20 of a motor vehicle 3. Where the rotor shaft 11 protrudes axially from the axial flux machine 1, a torque transmission element, for example a gearbox or a shaft, is connected, which transmits the torque of the axial flux machine 1 to one or more wheels of the vehicle 3. On the other side of the axial flux machine 1, on which the rotor position sensor 8 already shown in Figure 1 can be seen, the drive train housing 26 is open. On this side, in particular, an essentially identical axial flux machine 1, also with a downstream torque transmission element, which also drives one or more wheels of the motor vehicle 3, can be attached.The two axial flow machines 1 are connected by screwing the end faces of the drive train housings 26 together. The necessary screw holes 24 can be seen in Figure 2 on the outer edge of the drive train housing 26.

[0058] To ensure that the two axial flux machines 1 can be positioned very closely axially one behind the other, thus achieving a very compact design for the corresponding electric axle drive train 20, the rotor position sensor 8, its mounting elements, and its electrical cables 19 must not be axially space-defining. Figures 2 and 3 show how a very compact axial design of the rotor position sensor 8 is possible, which also minimizes the axial space required for the sensor mounting elements and the electrical cables 19.

[0059] Figure 2 shows that, in this exemplary embodiment, three cables run radially outward as electrical lines 19 from the rotor position sensor 8 on the front side of the motor housing 17 and then exit the drive train housing 26 through an angled bore or a cable gland in the flange area of ​​the drive train housing 26. To save axial space, several thin cables were arranged side by side. This requires less axial space than a cable with a round cross-section that contains all the required wires.

[0060] Figure 3 alternatively shows an electrical line 19 designed as a cable with a flat cross-section, for example a flat cable or ribbon cable. In order for the cables to be routed radially outwards along the housing section 18, the cables must of course rest on the housing section 18, just as the fastening tabs 25 of the sensor housing 16 must rest axially on the housing section 18 designed as a side wall in order to be axially screwed to the side wall. To save axial installation space, the fastening tabs 25 and the lines 19 may only be arranged next to one another and not one above the other, whereby next to one another and one above the other refer to a viewing direction along the axis of rotation of the rotor 7, frontally onto the front side of the motor housing 17.In addition, the lines 19 and fastening tabs 25 must be arranged in such a way that this requirement can still be met if the second axial flux machine 1 is mounted in front of the first axial flux machine 1 rotated by 180° about the mirror axis.

[0061] The requirement that the fastening tabs 25 and the lines 19 may only be arranged next to each other but not one above the other then refers to all fastening tabs 25 and all lines 19 of the two rotor position sensors 8 installed in the corresponding axle drive train 20.

[0062] Openings are provided in the respective sensor housing 16 through which the lines 19 can be laid from the active part of the rotor position sensor 8 to the rear of the sensor housing 16 or the housing section 18. And starting from the opening through which the lines 19 are pulled, recesses extend to the edge of the sensor housing 16, partially reducing the material thickness of the sensor housing 16 to the axial level of the front side of the housing section 18. In addition, the fastening tabs 25 are arranged offset on the circumference to the openings for the lines 19. Through these openings and adjacent recesses on the rear of the sensor housing 16, the lines can also be guided radially outwards in the area of ​​the sensor housing 16 at the same axial level that they also occupy radially further out on the housing section 18.

[0063] Since the end face of the drive train housing 26, i.e. the surface of the drive train housing 26 with which the two housing halves touch when two axial flux machines 1 are arranged next to one another, is not round, but rather, as can be seen in Figure 2, there is a point at which the housing contour is drawn radially further outwards than on the remaining circular circumferential area, the two axial flux machines 1 can only be screwed together in a single position. The geometries of the two drive train housings 26 are rotated by 180° to one another. This rotation or mirror axis of the geometry then lies in the plane of the two touching housing end faces, intersects the rotation axis of the rotors 7 orthogonally and runs through the center of the housing area that is drawn radially further outwards.If this rotation or mirror axis were drawn in Figure 2, the rotation or mirror axis would run parallel to the lines 19, offset slightly downwards, so that the rotation or mirror axis would intersect the rotation axis of the rotor 7. Because the lines 19 are not located on the rotation or mirror axis, but are offset from it and do not intersect the rotation or mirror axis, the lines 19 of the two adjacent axial flux machines 1 do not meet.

[0064] Figure 2 shows that there is an area below the lines 19 and also below the rotation or mirror axis in which no raised elements are arranged on the housing section 18. A further recess is also provided there in the sensor housing 16 of the rotor position sensor 8, and the recess for the passage of the lines 19 is widened on one side radially outside on the drive train housing 26. All of these measures ensure that space is reserved for the lines 19 of the adjacent axial flux machine 1 and that the two axial flux machines 1 can be arranged very close to one another axially without them accidentally touching or even damaging each other.

[0065] Figure 2 also shows that in the sensor housing 16 of the rotor position sensor 8, the recesses for the cables 19 are not located centrally between two mounting brackets 25. In other words, the mounting brackets 25 are arranged asymmetrically to the cables 19 and the rotation or mirror axis. This ensures that the mounting brackets 25 and mounting screws of the two adjacent axial flux machines 1 do not collide with other mounting brackets 25, mounting screws, cables 19, or cable clamps.

[0066] Figure 3 shows two rotor position sensors 8 in the arrangement in which they are located relative to one another when they are mounted on two adjacent axial flux machines 1 of an axle drive train 20. In order to be able to distinguish between the two rotor position sensors 8 more easily, the upper rotor position sensor 8 is shown in dashed lines. The lower rotor position sensor 8 is shown in solid lines. It can be clearly seen in Figure 3 that the fastening tabs 25 of the two rotor position sensors 8 are arranged offset from one another on the circumference and do not touch one another. The example shows three fastening tabs 25 per rotor position sensor 8. However, using the principle of fastening tabs 25 arranged asymmetrically to the rotation or mirror axis, even more fastening points per rotor position sensor 8 can be realized (for example six) without causing unwanted collisions.In this embodiment, the rotation or mirror axis of the sensor geometries is located parallel to the lines 19 directly in the middle between the two corresponding cable harnesses.

[0067] As an alternative embodiment, Figure 3 does not show several individual lines 19 per rotor position sensor 8, but rather a cable with a flat cross-section (flat cable, ribbon cable). Furthermore, for both rotor position sensors 8, the respective lines 19 are arranged directly next to a fastening tab 25 of the respective rotor position sensor 8. This makes it possible to use the fastening tab 25 for fastening the lines 19 and reduces the number of points on the circumference of the sensor arrangement where geometric elements of adjacent rotor position sensors 8 must interlock. This also has advantages in terms of installation space, as geometric elements belonging to the same rotor position sensor 8 can be moved closer together on the circumference than geometric elements of adjacent assemblies, since larger distances must be maintained between the geometric elements of adjacent assemblies for the longer tolerance chains and the greater required assembly clearance.

[0068] Figure 3 also shows that a recess is provided in the sensor housing 16 of the other rotor position sensor 8 in front of each line 19 of one rotor position sensor 8. It is advisable to make the recess in the sensor housing 16, which is provided for the lines 19 of the other rotor position sensor 8, wider than the recess for the lines 19 of the separate rotor position sensor 8. This ensures that the lines 19 are well guided in the recess of their own rotor position sensor 8 and fit into the recesses of the neighboring sensors even in the event of position deviations between the two rotor position sensors 8, which cannot be completely avoided.

[0069] Figure 3 shows two rotor position sensors 8 arranged next to one another in a perspective view. The two rotor position sensors 8, which can be distinguished in Figure 3 by the use of a solid line and a dashed line, can have direct contact or can be arranged at a short distance from one another.

[0070] Figure 4 shows a further embodiment of an axial flux machine 1 with a rotor position sensor 8 arranged radially inside the rotor shaft 11. In the embodiment shown in Figure 4, the housing section 18 of the stator 4 is drawn axially past the first rolling bearing 13 radially inward and supports the rolling bearing 13 on the bearing inner ring. In addition, the inner region of the housing section 18, which is shaped like a bearing seat, serves as a support for the rotor position sensor 8. In this embodiment, the housing section 18 takes on almost all the functions that the sensor housing 16 had in the previously described embodiment. The cover-like sensor housing 16 of the active rotor position sensor 8 closes the inner opening in the housing section 18 designed as a stator side wall and protects the rotor position sensor 8 from contamination.

[0071] Alternatively, the housing section 18 can also be pulled completely inward. If the sensor housing 16, as in the first embodiment of Figures 1-2, is designed to be sufficiently robust and connected to the housing section 18, the sensor housing 16 can also be used to support the first rolling bearing 13. The sensor housing 16 can then form the entire bearing seat or, if the sensor housing 16 replaces, for example, the inward-facing web on the housing section 18 of the first embodiment, serve as an axial stop for the first rolling bearing 13. Figure 4 further shows that the active rotor position sensor 8 in this embodiment is pressed into the cylindrical inner part of the housing section 18.To make adjusting the axial position of the active rotor position sensor 8 as easy as possible, an adjusting ring 22 is located between the sensor housing 16 of the active rotor position sensor 8 and the shoulder 21 of the housing section 18, which serves as an axial stop during press-in. By selecting an adjusting ring 22 with a suitable axial thickness, it is easy to ensure that the active rotor position sensor 8 is pressed into the correct axial position. This principle of adjusting the axial distance between the active and passive sensor parts using an adjusting element with variable thickness on the active rotor position sensor 8 can also be applied to the first embodiment. There, an adjusting ring or an adjusting plate, the axial thickness of which is selected as required, can be arranged between the housing section 18 and the sensor housing 16.

[0072] In the embodiment of Figure 4, the passive part of the sensor, i.e., the sensor target 9, is formed from or with the rotor shaft 11. A circumferentially arranged sequence of elevations and depressions is arranged on the end face of the rotor shaft 11 and is fixedly related to the position of the rotor magnets.

[0073] What the embodiments of Figures 1-4 have in common is that the rotor shaft 11 is mounted relative to the first stator body 5 via a first rolling bearing 13 and relative to the second stator body 6 via a second rolling bearing 14, wherein the rotor position sensor 8 with the sensor target 9 is arranged radially inside the first rolling bearing 13. The rotor position sensor 8 and / or the sensor target 9 has / has an axial overlap region 15 with the first rolling bearing 13, which likewise contributes to an axially compact configuration of an axial flux machine 1. The rotor position sensor 8 has a substantially cylindrical sensor housing 16, which is arranged radially at least in sections within the annular disk-shaped stator body 5 and axially projects at least in sections into the first annular disk-shaped stator body 5.Figure 5 shows an electric axle drive train 20 comprising a first axial flux machine 1 driving a first vehicle wheel and a second axial flux machine 1 driving a second vehicle wheel, wherein the axial flux machines 1 are essentially structurally identical. It can be clearly seen that the rotor position sensor 8 of the first axial flux machine 1 and the rotor position sensor 8 of the second axial flux machine 1 are located directly opposite each other in the electric axle drive train 20.

[0074] The terms "radial", "axial", "tangential" and "circumferential direction" used in this application always refer to the axis of rotation of the axial flux machine 1. The terms "left", "right", "top", "bottom", "above" and "below" serve only to clarify which areas of the figures are currently being described in the text. The later embodiment of the invention can also be arranged differently. Furthermore, the invention is not limited to the embodiments shown in the figures. The above description is therefore not to be regarded as limiting, but as explanatory. The following patent claims are to be understood in such a way that a named feature is present in at least one embodiment of the invention. This does not exclude the presence of further features.If the patent claims and the above description define 'first' and 'second' features, this designation serves to distinguish between two similar features without establishing a ranking.

[0075] List of reference symbols

[0076] 1 axial flux machine

[0077] 2 Drivetrain

[0078] 3 Motor vehicle

[0079] 4 Stator

[0080] 5 Stator body

[0081] 6 Stator body

[0082] 7 Rotor

[0083] 8 Rotor position sensor

[0084] 9 Sensor target

[0085] 10 Coverage area

[0086] 11 Rotor shaft

[0087] 12 hollow shaft

[0088] 13 rolling bearings

[0089] 14 rolling bearings

[0090] 15 Coverage area

[0091] 16 sensor housings

[0092] 17 Engine housing

[0093] 18 Housing section

[0094] 19 Management

[0095] 20 axle drive train

[0096] 21 Shoulder

[0097] 22 Adjustment ring

[0098] 23 threaded holes

[0099] 24 screw holes

[0100] 25 mounting tabs

[0101] 26 Drivetrain housing

Claims

Claims 1. Electric axial flux machine (1), in particular for a drive train (2) of a hybrid or fully electric motor vehicle (3), wherein the axial flux machine (1 ) has a stator (4) with a first annular disk-shaped stator body (5) and a rotor (7) axially spaced from the stator body, and the axial flux machine (1 ) further comprises a rotor position sensor (8) with a sensor target (9) by means of which the position of the rotor (7) relative to the stator (4) can be determined, characterized in that the rotor position sensor (8) with the sensor target (9) is positioned radially within the first annular disk-shaped stator body (5) with at least one sectionally axial overlap area (10) with the first stator body (5) within the axial flux machine (1 ).

2. Axial flux machine (1 ) according to claim 1 , characterized in that the rotor (7) comprises a rotor shaft (11 ) designed at least partially as a hollow shaft (12) and the sensor target (9) is arranged in the hollow shaft (12).

3. Axial flux machine (1 ) according to claim 2, characterized in that the rotor position sensor (8) engages axially at least partially, preferably completely, in the hollow shaft (12).

4. Axial flux machine (1) according to one of the preceding claims, characterized in that the rotor shaft (11 ) relative to the first stator body (5) via a first rolling bearing (13), wherein the rotor position sensor (8) with the sensor target (9) is arranged radially inside the first rolling bearing (13).

5. Axial flux machine (1 ) according to claim 4, characterized in that the rotor position sensor (8) and / or the sensor target (9) have / have an axial overlap area (15) with the first rolling bearing (13).

6. Axial flux machine (1) according to one of the preceding claims, characterized in that the rotor position sensor (8) is a substantially cylindrical sensor housing. (16) which is arranged radially at least partially within the annular stator body (5) and projects axially at least partially into the first annular stator body (5).

7. Axial flux machine (1 ) according to claim 6, characterized in that the axial flux machine (1 ) is received in a motor housing (17), wherein the motor housing (17) has a housing section (18) extending in a radial plane to which the sensor housing (16) is attached.

8. Axial flux machine (1 ) according to claim 7, characterized in that the rotor position sensor (8) has at least one electrical line (19) which extends radially outwards over the housing section (18). Electric axle drive train (20) comprising a first axial flux machine (1) according to one of claims 1-8 and a second axial flux machine according to one of claims 1-8. Electric axle drive train (20) according to claim 9, characterized in that the rotor position sensor (8) of the first axial flux machine (1 ) and the rotor position sensor (8) of the second axial flux machine (1 ) are directly opposite each other in the electric axle drive train (20).

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