Stator arrangement for an electric machine of a motor vehicle that is at least partially electrically powered, as well as an electric machine

Abstract

The invention relates to a stator arrangement (32) for an electric machine (12) of an at least partially electrically powered motor vehicle (10), wherein at least a first surface (26) of a stator (18) of the stator arrangement (32) faces at least a first rotor (22) of the electric machine (12), and wherein at least on the first surface (26) a first sensor wire (34) of the stator arrangement (32) is formed in an area, which is designed to detect contact between the first surface (26) and the at least one first rotor (22). The invention further relates to an electric machine (12).

Description

[0001] The following invention relates to a stator arrangement for an electric machine of an at least partially electrically powered motor vehicle, wherein at least a first surface of a stator of the stator arrangement faces at least a first rotor of the electric machine. The invention further relates to a corresponding stator arrangement.

[0002] Electrical machines, such as axial flux machines, are already known from the prior art. These machines typically feature an inner stator and an outer rotor and are increasingly used, particularly in the automotive sector, due to their high power density and efficiency. The stator can consist of stator windings, an iron core, a housing, and, for example, plastic end caps on both sides. It is known that the length of an air gap forms a bottleneck in the axial flux machine. A small air gap may be necessary to achieve high power density and efficiency. However, this small air gap generates a high axial force, leading to deformation and displacement of the rotor, especially at the edge of the rotor disk.Furthermore, given the relatively large diameter of the machine, achieving a uniform air gap between the stator and rotor during production is very difficult. Any deformation of the stator, such as a dent, directly affects the air gap. Finally, external vibrations of the electric machine, as well as aging and fatigue of the rotor material, exacerbate the situation. Therefore, the risk of a so-called touchdown—that is, physical contact between the rotor and stator—is very high, particularly in an axial flux machine.

[0003] Detecting a touchdown in a motor vehicle is very difficult. The rotor displacement, for example in the axial direction, depends on the operating point of the axial flux machine and environmental variables such as temperature and acceleration. Therefore, a touchdown can only occur briefly under certain conditions, and the machine can also recover from the touchdown. At the beginning of a touchdown, the frictional force on the rotor increases slightly. This cannot be detected using the current or voltage signals of the electric machine. As the contact intensifies, the rotor begins to rub against the plastic disc, which can cause slight noise and increases the air pressure inside the electric machine. Finally, the magnets on the rotor contact the windings or the iron cores in the stator, causing a short circuit. Alternatively, rotor magnets may be partially cut off or fall off.These detached parts could pile up somewhere in the air gap and completely block the rotation of the rotor.

[0004] At the vehicle level, fault detection is only possible if a short circuit in the electric motor or a blocked axle of the assembly occurs, which is the serious consequence of a touchdown. However, there is no indicator of a touchdown in the electric motor itself. The contact can only be detected after the electric motor has been disassembled.

[0005] In current technology, touchdowns are reported on the test bench using various methods. However, there is currently no method to directly detect touchdowns in the vehicle itself.

[0006] EP 3245719 A1 describes an axial flux machine. The machine has a stator comprising a stator housing containing a plurality of stator bars spaced circumferentially around an axis of the machine, and a rotor comprising a set of permanent magnets mounted for rotation around the axis of the machine. The rotor is spaced from the stator along the axis of the machine to define a gap between the stator and the rotor, by ensuring that the magnetic flux in the machine generally travels in an axial direction. The machine also includes a hub assembly comprising a rotating hub and a support, separated by a bearing to allow the hub to rotate relative to the support. The rotating hub comprises a hub flange, and the support comprises a support flange, each flange being axially spaced from the other.The machine further comprises a partition for mounting the hub assembly and the stator, the partition being attached to the mounting flange of the hub assembly and the stator housing. The rotor comprises a first and a second rotor arranged on either side of the stator, the first rotor being attached to the near flange and the second rotor being attached only to the first rotor, the first and second rotors together forming a U-shaped rotor extending transversely and on both sides of the stator and rotatable about the axis of the machine relative to the stator.

[0007] The object of the present invention is to create a stator arrangement and an electrical machine by means of which improved monitoring of a potential defect / touchdown of the electrical machine can be achieved.

[0008] This problem is solved by a stator arrangement and an electrical machine according to the independent claims. Advantageous embodiments are specified in the dependent claims.

[0009] One aspect of the invention relates to a stator arrangement for an electric machine of an at least partially electrically powered motor vehicle, wherein at least a first surface of a stator of the stator arrangement faces at least a first rotor of the electric machine.

[0010] It is provided that at least on the first surface a first sensor wire of the stator arrangement is formed in a flat shape, which is designed to detect a contact between the first surface and the at least one first rotor.

[0011] In particular, this allows for the detection of contact between the sensor wire, especially its surface, and the rotor during a so-called touchdown, for example, due to a bulge in the stator or rotor. Based on a change in resistance, such as that of the sensor wire, it can be determined that such a touchdown has occurred. This also enables measurements to be taken while the vehicle is in operation, allowing for early detection of potential faults.

[0012] In particular, the invention proposes a sensor wire extending around the circumference and surface of the stator, especially in the area towards the air gap, to allow for early conclusions to be drawn about the mechanical bearing of the rotor, its impacts on the stator (especially so-called touchdowns), and the condition of the electric machine in the event of damage to the wire. Conversely, if the rotor touches and / or rubs against the stator during operation of the electric machine, the continuous, thin wire, embedded, for example, in a plastic layer, is damaged, allowing its resistance increase to be measured in order to detect the damage and to take early countermeasures to protect the electric machine.

[0013] Particularly with small air gap dimensions for increased performance, or even with normal air gap dimensions under high load and / or shear forces on a corresponding shaft, monitoring of air gap compliance can be enabled by detecting damage in the event of a hard touchdown or continuous light contact and grinding between the rotor and stator. According to the invention, a continuous wire / sensor wire is essentially arranged in a corresponding plastic disc facing the plastic layer on the stator towards the air gap. This wire covers the circumference and surface of the disc and, if damaged, for example by a touchdown, impact, or scraping, exhibits a measurable increase in resistance.

[0014] In particular, this makes it possible to detect damage to the sensor wire by measuring its continuity, and thus to infer mechanical damage to the surface and therefore a touchdown of the rotor onto the stator.

[0015] According to an advantageous embodiment, the stator assembly for an axial flux machine is designed as an electric machine. In particular, the axial flux machine requires a correspondingly small air gap to achieve a high power density. Specifically, a suitable plastic disc is formed between the rotor and the air gap, particularly on the rotor itself, which prevents contact between the rotor and stator. It can be provided that at least the first sensor wire is arranged within this plastic disc. Thus, reliable monitoring of a potential touchdown can be implemented in an axial flux machine.

[0016] Furthermore, it is advantageous if the stator assembly additionally has a second surface facing a second rotor of the axial flux machine, wherein the second surface has a second sensor wire extending across its entire area, which is designed to detect contact between the second surface and the second rotor. Thus, the axial flux machine can be provided, in particular, as a double rotor with one stator. Such an axial flux machine, in particular, has a high efficiency and a high power density, making it especially suitable for automotive applications. With the presented design, contact between the first rotor and the second rotor can now be detected via a corresponding sensor wire. Therefore, reliable monitoring of an axial flux machine with two rotors and one stator can be carried out.

[0017] It has also proven advantageous to connect the first and second sensor wires. For example, they can be connected along the same axis. This allows a single evaluation unit to easily detect a touchdown on both the first and second rotors. This enables a more compact monitoring system.

[0018] It is also advantageous if the axial flux machine is designed as an H-type axial flux machine. In particular, the H-type axial flux machine can be used, for example, as a drive motor for electric vehicles. Due to their compact design and high power density, H-type axial flux machines are especially well-suited for use in electric drive systems of motor vehicles, particularly in cases where high torque and a compact design are required. One example is the use of H-type axial flux machines as drive motors in electric or hybrid sports cars. Another potential application for H-type axial flux machines in motor vehicles is their use as range extenders in plug-in hybrid vehicles. Here, a small H-type axial flux machine can be operated as a generator to recharge the vehicle's battery when needed, thus increasing the vehicle's range.In particular, the H-type axial flux engine has advantages in terms of power density and compactness, which is why it can be used advantageously in motor vehicles.

[0019] It is also advantageous if at least the first sensor wire is arranged in a spiral or meandering pattern on the first surface. This allows for monitoring of the surface and thus the stator arrangement over a large area. As a result, corresponding touchdowns can be reliably detected across a large surface area.

[0020] According to a further advantageous embodiment, at least one end of the first sensor wire and one end of the first sensor wire terminate at the same location on the first surface. In particular, they terminate at essentially the same location. This allows for simple contact with, for example, a higher-level power source or a higher-level evaluation unit. Short wires can thus be routed out of the stator, enabling the reliable detection of a potential touchdown signal.

[0021] It is also advantageous if at least the first sensor wire is connected to a power source. In particular, the power source can continuously supply current through the first sensor wire. Based on the absence of current detection, it can then be reliably concluded that, for example, the sensor wire is broken or defective. This makes it possible to easily detect a defect in the electrical machine.

[0022] It is also advantageous if at least the first sensor wire is connected to an evaluation unit. The evaluation unit can, in particular, be in the form of an electronic computer. Based on a corresponding electrical signal within the sensor wire, the evaluation unit can then conclude that, for example, a defect in the electrical machine exists. The evaluation unit can then transmit a corresponding control signal to a higher-level electronic computer so that appropriate countermeasures can be initiated.

[0023] Another aspect of this concerns an electric machine of a motor vehicle that is at least partially electrically powered, with at least one first rotor and with a stator arrangement according to the previous aspect.

[0024] The electric machine can be designed in particular as an axial flux machine, especially as a double-rotor axial flux machine.

[0025] Furthermore, the invention also relates to a motor vehicle that is at least partially electrically powered and has at least one electric machine according to the preceding aspect.

[0026] Advantageous designs of the stator arrangement are to be regarded as advantageous designs of the electric machine as well as the motor vehicle.

[0027] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment and from the drawings. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0028] This shows: Fig. 1 a schematic side view of an embodiment of a motor vehicle with an embodiment of an electric machine; Fig. 2 a schematic representation of an embodiment of an axial flux machine; Fig. 3 a schematic top view of an embodiment of a surface of a stator; Fig. 4 a further schematic representation of another embodiment on a surface of a stator; Fig. 5 a schematic perspective view of an embodiment of a stator arrangement; and Fig. 6 a schematic sectional view of an embodiment of a stator arrangement.

[0029] In the figures, identical or functionally equivalent elements are provided with the same reference symbols.

[0030] Fig. Figure 1 shows a schematic view of an embodiment of a motor vehicle 10. The motor vehicle 10 is designed as a motor vehicle 10 that is at least partially electrically powered or fully electrically powered. For this purpose, the motor vehicle 10 has an electric machine 12. In the following embodiment, the electric machine 12 is designed in particular as a drive machine. However, the electric machine 12 can also be provided as a so-called range extender.

[0031] Fig. Figure 2 shows a schematic perspective view of an embodiment of the electric machine 12. In the present embodiment, the electric machine 12 is specifically designed as a so-called axial flux machine 14. In the following embodiment, the axial flux machine 14 comprises a housing 16, a stator 18, a stator housing 20, a first rotor 22 with magnets 23, and a second rotor 24 with magnets 25, wherein the stator 18 is arranged centrally between the two rotors 22, 24. The stator 18 has corresponding iron cores and stator windings. End plates 30, 32 may also be formed on the stator 18 facing the two rotors 22, 24.

[0032] The axial flux machine 14 according to the embodiment shown is in particular designed as a so-called double rotor machine and in particular provided as an H-type axial flux machine 16.

[0033] The end plates 30, 32 are provided in particular as plastic discs, so-called stator discs.

[0034] Fig. Figure 3 shows a schematic top view of an embodiment of a stator arrangement 32. The stator arrangement 32 has at least the first surface 26 of the stator 18. Furthermore, the stator arrangement 32 has a first sensor wire 34 on the surface 26, which is designed to detect contact between the first surface 26 and the at least one first rotor 22.

[0035] This shows Fig. 3 in particular that the first sensor wire 34 is arranged in a substantially meandering pattern on the first surface 26.

[0036] Furthermore, the Fig. 3, that at least a first end 36 of the first sensor wire 34 and a second end 38 of the sensor wire 34 terminate at the same location on the first surface 26. In particular, these ends 36, 38 can then be coupled to a power source 40. Furthermore, the power source 40 can in turn be coupled to an evaluation device 42.

[0037] Fig. Figure 4 again shows the stator arrangement 32 in a further embodiment. In the following embodiment, it is shown in particular that the sensor wire 34 can be arranged essentially in a spiral shape on the surface 26.

[0038] Fig. Figure 5 shows a schematic perspective view of an embodiment of the stator arrangement 32, wherein in the following exemplary embodiment the stator arrangement 32 is provided in particular for an axial flux machine 14 with a double rotor. The first surface 26 and the second surface 28 of the stator 18, which is not shown in this figure for clarity, can be provided in the form of a plastic disk, so that the stator 18 is arranged between the two surfaces 26, 28. The first sensor wire 34 is formed on the first surface 26. A second sensor wire 44 can be formed on the second surface 28. In the following exemplary embodiment, both are formed in a spiral shape. The Fig. 5 furthermore, that the first sensor wire 34 and the second sensor wire 44 can be connected to each other via a connection 46. Thus, evaluation can take place in a simple manner. In other words, in the following embodiment, the first sensor wire 34 has the first end 36 and the second sensor wire 44 has the second end 38.

[0039] Fig. Figure 6 shows a schematic perspective view of an embodiment of the sensor arrangement 32. In the following embodiment, the sensor arrangement 32 is axially supported about an axis 48. In particular, corresponding bearings 50 are provided for this purpose. Furthermore, the Fig. 6 the iron core 52 and corresponding stator windings 54.

[0040] In particular, the Fig. 1 to Fig. 6 the axial flux machine 14, in which an early touchdown can be determined or detected based on the stator arrangement 32 according to the invention. In particular, the figures show a simplified inner stator 18 with the corresponding stator disks, in the following exemplary embodiment referred to in particular as surfaces 26, 28. The stator windings 54 and the iron core 52 are covered with the corresponding plastic disks, which are ultimately screwed to the stator housing 20. The plastic cover is not only held in place by the windings and iron cores 52, but also ensures a smooth surface of the stator 18. The thin sensor wires 34, 44 are embedded in the stator disks. The corresponding wire ends lead through the stator housing 20 and are connected to a circuit, for example an inverter, for power supply and monitoring.The wires can be made from any conductive material and in any shape, for example, round, rectangular, or trapezoidal. As shown, the rectangular copper wire is chosen as an example to cover a larger area of ​​the surface 26, 28 of the plastic disc. The sensor wire 34, 44 can be arranged in any shape, radially or tangentially, or in a combination of both. The shape of the wire influences the probability of successfully detecting a so-called touchdown.

[0041] Two possible arrangements of the sensor wires 34, 44 are shown in the Fig. 3 and Fig. 4 shown, for example in a so-called daisy shape, as in the Fig. 3 and also the spiral shape, as in the Fig. Figure 4 shows that the incoming and outgoing wires are arranged very close together to obtain the most closed surface possible in the magnetic field. In the daisy-like shape according to the Fig. 4. The distance between the radial wires and the wire length in the radial direction can be adjusted so that the surface 26, 28 is maximally covered for touch detection. In the case of the spiral shape according to Fig. 4. A small spiral deviation of the wires can increase the possibility of touchdown detection.

[0042] The two ends of the wires are connected to a current / voltage source or a resistance sensor. If, as shown in the figures, a current source 40 is connected to the embedded wire, the probability of successful touch detection increases.

[0043] The sensor wires 34, 44 can be constructed in any desired shape and arranged radially, tangentially, or in a combination thereof. The entire circuit of sensor wires 34, 44 is embedded in the stator disk. This means that a corresponding wire set and circuit are required for each stator surface. Therefore, this type of stator disk can be used for touchdown detection in axial flux machines 14 with one rotor and one stator or with two rotors. Alternatively, the sensor wires 34, 44 can be arranged, as is particularly evident in Fig.As shown in Figure 5, the wires can also be mounted on both stator disks with or without phase shift. The wires can be spirally integrated symmetrically into the plastic disks on both sides without phase shift. The two sensor wires 34, 44 are internally connected through the stator 18 to eliminate the induced voltage in the sensor wires 34, 44. Only one current source 40, which supplies a constant current, is connected to the two ends 36, 38 of the sensor wires 34, 44 for touch detection on both sides.

[0044] The proposed stator arrangement 32 with the embedded sensor wires 34, 44 is presented, in particular, on the plastic discs to detect the contact or touchdown of an axial flux machine 14 at an early stage, before a critical failure occurs. Physical damage to the surfaces 26, 28 of the axial flux machine 14 cannot be detected until it leads to serious consequences, such as a short circuit or a blocked axis of the unit. The main causes of physical contact between the stator 18 and the rotors 22, 24 can be deformation and displacement of the rotor 22, 24 or a dent in the stator 18. Both causes can be detected using the stator arrangement 32 according to the invention.

[0045] The deformation and displacement of rotors 22 and 24 generate a high axial force, and the vibrations cause the rotor discs to deform and displace. After touchdown, rotors 22 and 24 begin to grind against the plastic discs. Soon, the scratch on the plastic discs will cross the embedded wire, damaging the thin wire. In this case, the entire circuit will show increased resistance or a break, which can be easily monitored by the electrical circuit.

[0046] Furthermore, the stator surface can bulge due to thermal or mechanical stresses or a product defect, which can lead to a touchdown. This deformation of the stator 18 puts stress on the embedded wire in the plastic disks and damages the thin wire. Therefore, increased resistance or an open circuit can be detected before a corresponding bulge on the stator 18 touches the rotor 22, 24. Reference symbol list 10 motor vehicle 12 electric machine 14 Axial flux machine 16 cases 18 Stator 20 stator housings 22 first rotor 23 magnets 24 second rotor 25 magnets 26 first surface 28 second surface 30 End plate 32 End plate 34 first sensor wire 36 first end 38 second end 40 Power source 42 Evaluation unit 44 second sensor wire 46 connection 48 axle 50 storage 52 iron core 54 Stator winding 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] EP 3245719 A1

[0006]

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