Electric axial flux machine

Abstract

An electric axial flux machine (1), particularly for use within a powertrain of a hybrid or fully electric motor vehicle, comprising a stator (2) and a rotor (4) separated from the stator (2) by an air gap (3), wherein the stator (2) is received in a cup-shaped annular housing (5) with a housing base (6) extending radially in the direction of the rotation, wherein the housing base (6) extends through the air gap (3) between the stator (2) and the rotor (4), and the housing (5) is closed on the side axially opposite the housing base (6) by a housing cover (7), and the housing cover (7) has at least one first positioning means (8) projecting axially out of the housing cover (7) or at least one projecting axially into the housing cover (7), which interacts with a corresponding second positioning means (9) on the stator (2) in such a way thatthat the position of the stator (2) relative to the housing cover (7) is fixed, characterized in that the second positioning means (9) is designed as a recess (11) extending axially into the stator (2).

Description

The present invention relates to an electric axial flux machine, in particular for use within a drive train of a hybrid or fully electric motor vehicle, comprising a stator and a rotor separated from the stator by an air gap. Electric motors are increasingly being used in motor vehicles to provide alternatives to combustion engines that require fossil fuels. Considerable efforts have already been made to improve the everyday usability of electric drives and to offer users the familiar driving comfort. A detailed description of an electric drive system can be found in an article in the journal ATZ, 113th year, 05 / 2011, pages 360-365, by Erik Schneider, Frank Fickl, Bernd Cebulski, and Jens Liebold, entitled: "Highly Integrated and Flexible Electric Drive Unit for E-Vehicles," which likely represents the next state of the art. This article describes a drive unit for a vehicle axle, comprising an electric motor arranged coaxially with a bevel gear differential. 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. Often, both the stator and rotor are largely disk-shaped. Axial flux machines are particularly advantageous when the available axial installation space is limited in a given application. This is frequently the case, for example, with both of the electric drive systems for electric vehicles described earlier. In addition to the reduced axial length, another advantage of the axial flux machine lies in its comparatively high torque density. This is due to the larger air gap area available within a given installation space compared to radial flux machines.Furthermore, a smaller volume of iron is required compared to conventional machines, which has a positive effect on the efficiency of the machine. Due to its disc-shaped main components, an axial flux machine is particularly well-suited for applications where a very short overall length of the electric motor is crucial and a relatively large motor diameter is still acceptable. Therefore, when developing such axial flux machines, it is generally advisable to aim for the shortest possible design, while ensuring that the outer diameter of the machine is no larger than absolutely necessary. For axial flux machines used in motor vehicles, there are also always additional requirements for low weight, high power density, and low cost. From WO 2021 / 172 793 A1, an axial flux machine according to the preamble of claim 1 is known. Regarding further state of the art, reference is made to EP 2 273 655 A1 and DE 10 2021 108 951 A1. The object of the invention is therefore to provide an electric axial flux machine that is inexpensive to manufacture and easy to assemble. This problem is solved by an electric axial flux machine, particularly for use within a powertrain of a hybrid or fully electric motor vehicle, comprising a stator and a rotor separated from the stator by an air gap, wherein the stator is received in a cup-shaped annular housing with a housing base extending radially, wherein the housing base extends through the air gap between the stator and the rotor, and the housing is closed on the side axially opposite the housing base by a housing cover, wherein the housing cover has at least one first positioning means projecting axially from the housing cover or at least one projecting axially into the housing cover, which interacts with a corresponding second positioning means on the stator in such a way thatthat the position of the stator relative to the housing cover is fixed. Preferably, the housing cover has at least one third positioning means projecting axially out of the housing cover or at least one third positioning means projecting axially into the housing cover, which interacts with a corresponding fourth positioning means on the housing in such a way that the position of the housing relative to the housing cover is determined. This offers the advantage that components of the axial flux machine can be positioned directly relative to each other via the components themselves, resulting in shorter tolerance chains and consequently more efficient use of installation space. The stator and housing are positioned directly using corresponding positioning elements, which are, for example, formed as recesses or protrusions on the housing cover. This approach allows for the shortest possible tolerance chains between the stator and housing cover, as well as between the housing and stator / housing cover. Furthermore, no additional assembly aids are required in the tooling, which can also positively impact ease of assembly and manufacturing costs. First, the individual elements of the claimed subject matter of the invention are explained in the order in which they are mentioned in the claim set, and subsequently, particularly preferred embodiments of the subject matter of the invention are described. 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 in the air gap between the stator and rotor to a rotational direction of the rotor of the axial flux machine. Depending on the application, it can 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 I-arrangement. In principle, it is also possible for multiple rotor-stator configurations of I-type and / or H-type to be arranged axially side by side. It would also be possible in this context to arrange several I-type rotor-stator configurations side by side in the axial direction. In particular, it is also preferred that the H-type and / or I-type rotor-stator configurations are essentially identical, so that they can be assembled modularly into a complete configuration. Such rotor-stator configurations can, in particular, be arranged coaxially to one another and be connected to a common rotor shaft or to multiple rotor shafts. The stator of the electrical axial flux machine according to the invention preferably comprises a stator body with several circumferentially arranged stator windings. 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 lamination stack with several laminated electrical steel sheets. 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 stator is housed in a casing. The casing can be a single piece or multi-piece. Preferably, the casing is made of plastic. The casing can be completely closed. It is also possible to provide openings in the casing, for example, to reduce weight or to provide access to a component. The rotor of an electric axial flux machine can be designed, at least in part, as a laminated rotor. A laminated rotor is layered in the axial direction. Alternatively, the rotor of an axial flux machine can also have a rotor carrier that is appropriately equipped with magnetic laminations and / or SMC material and with magnetic elements designed as permanent magnets. The permanent magnets can preferably be integrated into the pockets of the rotor lamination stack. Each pocket can contain either a single larger rotor magnet designed as a bar magnet or several smaller rotor magnets designed as permanent magnet elements. The rotor preferably comprises a plurality of rotor bodies. The rotor bodies are particularly preferably formed with substantially the same components, and especially with substantially identical components. It is most preferably that the rotor bodies are formed from rotor laminations of the same components, and especially with substantially identical components. The rotor bodies are therefore particularly preferably formed from a rotor lamination stack, which is composed of a plurality of laminated individual laminations, or rotor laminations, generally made of electrical steel, which are stacked and bundled on top of each other to form a stack, the so-called rotor lamination stack. The individual laminations can be held together in the rotor lamination stack by gluing, welding, or screwing. A rotor lamination stack can also, in particular, include permanent magnets inserted into the pockets of the rotor lamination stack or fixed circumferentially to the rotor lamination stack. A rotor shaft is a rotatably mounted shaft of an electric machine, to which the rotor or rotor body is coupled in a rotationally fixed manner. The electric axial flux machine can further comprise a control device. A control device such as that which 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. The electric axial flux machine is intended for use within the powertrain of a hybrid or fully electric motor vehicle. In particular, the electric machine is dimensioned to enable vehicle speeds greater than 50 km / h, preferably greater than 80 km / h, and especially greater than 100 km / h. The electric motor preferably has a power output greater than 30 kW, preferably greater than 50 kW, and especially greater than 70 kW. It is further preferred that the electric machine provides rotational speeds greater than 5,000 rpm, particularly preferably greater than 10,000 rpm, and most preferably greater than 12,500 rpm. 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 single structural unit. It is particularly possible for the electric axial flux machine and the transmission to be arranged in a common drive train housing. Particularly preferably, such a drive train housing can also form a connection structure for the axial flux machine. Alternatively, it would of course also be possible for the electric axial flux machine to have a motor housing and the transmission a transmission housing, with the structural unit then being achieved by fixing the transmission to the electric axial flux machine. This structural unit is occasionally also referred to as an e-axle. According to an advantageous embodiment of the invention, the first positioning means and / or the third positioning means can be formed integrally, particularly monolithically, with the housing cover. The advantage of this embodiment is that it further reduces manufacturing costs and improves ease of assembly. According to a further preferred embodiment of the invention, the first positioning means and / or the third positioning means may each be designed as a component separate from the housing cover. Such a separate component may, for example, be a keyway. Furthermore, according to another advantageous embodiment of the invention, the separate component may have a feedthrough for at least one electrical conductor from the housing. The advantage of this embodiment lies in the fact that integrating an additional function into the separate component allows for a higher degree of system integration, which can also contribute to simplified assembly and reduced manufacturing costs. According to a further particularly preferred embodiment of the invention, it can be provided that the first positioning means and the third positioning means are made in one piece, which can also have a positive influence on the manufacturing costs. According to the invention, the second positioning means is designed as a recess extending axially into the stator. The advantage is that such a recess can be implemented relatively easily in a stator, which again contributes to the cost-effective manufacture of the axial flux machine. In a further preferred embodiment of the invention, the housing cover may also have a cylindrical ring section extending axially towards the rotor, on which at least one fifth positioning means projecting radially into or out of the cylindrical ring section is provided, which interacts with a corresponding sixth positioning means on the housing such that the position of the housing relative to the housing cover is determined. This also provides a manufacturing-efficient method for positioning the components relative to each other. It may also be advantageous to further develop the invention such that the fifth positioning means is formed integrally, and in particular monolithically, with the cylindrical ring section, which can again provide manufacturing advantages. However, according to a further preferred embodiment of the invention, it may also be provided that the fifth positioning means is designed as a component separate from the cylindrical ring section, for example, as a key. Finally, the invention can also be advantageously implemented in such a way that the axial flux machine is configured in an I-arrangement. The invention will now be explained in more detail with reference to figures, without limiting the general concept of the invention. It shows: Fig. 1 an electric axial flux machine in a schematic axial sectional view, Fig. 2 a first embodiment of a stator of an electric axial flux machine in a schematic axial sectional view, Fig. 3 a second embodiment of a stator of an electric axial flux machine in a schematic axial sectional view, Fig. 4 a third embodiment of a stator of an electric axial flux machine in a schematic axial sectional view, Fig. 5 a fourth embodiment of a stator of an electric axial flux machine in a schematic axial sectional view, Fig. 6 a fifth embodiment of a stator of an electric axial flux machine in a schematic axial sectional view, Fig. 7 a sixth embodiment of a stator of an electric axial flux machine in a schematic axial sectional view, Fig.Fig. 8 shows a seventh embodiment of a stator of an electric axial flux machine in a schematic axial sectional view and a stator body in a perspective view. Fig. 9 shows an eighth embodiment of a stator of an electric axial flux machine in a schematic axial sectional view. Fig. 10 shows a ninth embodiment of a stator of an electric axial flux machine in a schematic axial sectional and a cross-sectional view. Fig. 11 shows a tenth embodiment of a stator of an electric axial flux machine in a schematic axial sectional and a cross-sectional view. Fig. 12 shows an eleventh embodiment of a stator of an electric axial flux machine in a schematic axial sectional view. Fig. 13 shows a twelfth embodiment of a stator of an electric axial flux machine in a schematic axial sectional view.Fig. 14 shows a thirteenth embodiment of a stator of an electric axial flux machine in a schematic axial sectional view, Fig. 15 shows a fourteenth embodiment of a stator of an electric axial flux machine in a schematic axial sectional view. Fig. 1 shows an electric axial flux machine 1, particularly for use within the powertrain of a hybrid or fully electric vehicle, comprising a stator 2 with a stator winding 23 and a rotor 4 separated from the stator 2 by an air gap 3. The axial flux machine 1 is configured in an I-arrangement, resulting in a structure of the axial flux machine 1 that is a mirror image of the radial plane of the rotor 4. Therefore, for the sake of clarity, reference numerals for the right stator have been omitted. However, it is understood that this is essentially a mirror image of the left stator 2. The stator 2 is housed in a pot-shaped, annular housing 5 with a radially extending housing base 6, the housing base 6 extending through the air gap 3 between the stator 2 and the rotor 4, and the housing 5 being closed on the side axially opposite the housing base 6 by a housing cover 7. The housing 5 thus resembles the shape of a donut. The housing 5 is sealed against the housing cover 7 via the sealing ring 28 and axially secured by means of the retaining ring 29. The housing cover 7 has at least one first positioning means 8 projecting axially from the housing cover 7 or at least one projecting axially into the housing cover 7, which interacts with a corresponding second positioning means 9 on the stator 2 such that the position of the stator 2 relative to the housing cover 7 is determined. Furthermore, the housing cover 7 can have at least one third positioning means 10 projecting axially from the housing cover 7 or at least one projecting axially into the housing cover 7, which interacts with a corresponding fourth positioning means 9 on the housing 5 such that the position of the housing 5 relative to the housing cover 7 is determined. This results in a number of configuration possibilities, which are explained in more detail below with reference to Figures 2-11. Figure 2 shows an embodiment in which the first positioning means 8 and the third positioning means 10 are each formed integrally, in particular monolithically, with the housing cover 7 and project axially from the housing cover 7. The positioning means 8 and 10 can, for example, be formed by means of a crimp. This gives the positioning means 8 and 10 a pin-like design, with the first positioning means 8 engaging in a corresponding recess (second positioning means 9) of the stator 2 and the second positioning means 10 engaging in a corresponding recess (fourth positioning means 19) of the housing 5 formed on the radial inner circumference of the housing 5. To also achieve centering of the components relative to each other, it is recommended to form at least three pin-like positioning means 8 and 10 on the circumference of the housing cover 7. If centering is achieved, e.g.,With a centering diameter, a pin-like positioning device 8,10 is sufficient for the comprehensive positioning of the corresponding component. Fig. 3 shows a slightly modified embodiment of Fig. 2, in which the first positioning means 8 and the third positioning means 10 are formed in one piece and are positioned in the radially inner circumferential region of the housing 5. The one-piece positioning means 8, 10 is also formed monolithically from the housing cover 7 by means of a crimp. A modification of the solution known from Fig. 3 is shown in Fig. 4. Here, the first positioning means 8 and the third positioning means 10 are combined but formed as a component 12 separate from the housing cover 7. The separate component 12 is a keyway and is positioned in the radially inner region of the housing 5. Positioning in the radially outer region of the housing 5 is also possible, as shown in Fig. 6. As can be seen in Fig. 7, in this embodiment the separate component 12 has a passage 14 for at least one electrical conductor 13 from the housing 5, the electrical conductor 13 being used to supply current to the stator winding 23. Figure 5 shows a slight modification of the embodiment already known from Figure 2. Here, however, the third positioning element 10 is designed as a recess into which a separate component 12, designed as a keyway, engages and effects the positioning of the housing 5 relative to the housing cover 7. It is of course also possible that the separate component 12 is integrally formed with the housing 5 and then engages as a pin-like positioning element 19 in the corresponding recess of the housing cover 7. Fig. 8 shows an alternative embodiment in which the second positioning means 9 is designed as a recess 11 extending axially into the stator 2. A plurality of such recesses 11 can extend radially through the annular stator yoke 21 of the stator body 20 on the side of the stator 2 facing the housing cover 7, serving as cooling channels 24. The stator body 20 also has stator teeth 22 extending axially from the stator yoke 21. The cooling channels 24 can thus be used to provide a recess 11 in the stator 2 into which the first positioning means 8 engages. The recess 11 then forms the second positioning means 9.For a stator 2 wound from a strip of sheet metal, it makes sense to capture the position between housing cover 7 and stator 2 as radially inwards as possible, since the wound stator 2 has the highest accuracy in this area. The cooling fluid 25 can be guided through the housing cover 7 via a cooling fluid inlet 26 and supplied to the cooling channels 24. The cooling fluid 25 then exits the stator area again through the outlet opening 27 in the radially upper region of the housing 5. The embodiment of Fig. 9 corresponds essentially to that of Fig. 8, except that here the cooling channel is formed into the housing cover 7. A pin-like positioning element 9 is then provided on the stator 2, which engages in the cooling channel of the housing cover 7. The cooling channel 24 thus constitutes the first positioning element 8 of the housing cover 7. Figures 10-11 show two embodiments in which the housing cover 7 has a cylindrical ring section 15 extending axially towards the rotor 4, on which at least one fifth positioning means 16 is formed, projecting radially into or out of the cylindrical ring section 15. This fifth positioning means 16 interacts with a corresponding sixth positioning means 17 on the housing 5 such that the position of the housing 5 relative to the housing cover 7 is determined. Figure 10 shows an embodiment in which the fifth positioning means 16 is formed integrally, in particular monolithically, with the cylindrical ring section 15. The positioning of the housing 5 can therefore be achieved, for example, via a splined connection (positive locking) on ​​the cylindrical ring section 15.As can be seen from the figures, the axial flux machine 1 in the illustrated embodiment has a housing cover 7 and a hub connected to the housing cover 7 by a welded connection, which forms the cylindrical ring section 15. If the housing cover 7 is centered over a diameter, a tooth-like positioning means 16 is sufficient to maintain the circumferential position, as shown in Fig. 10. Otherwise, at least three tooth-like positioning means 16 are required to additionally center the housing 5. In the embodiment of Fig. 11, the fifth positioning means 16 is designed as a component 18 separate from the cylindrical ring section 15, for example as a key. Figures 12-15 show further embodiments of the invention in which the housing base 6 and / or the housing cover 7 are also positioned above the stator 2. Otherwise, these embodiments correspond to those known from Figures 2-7. The invention is not limited to the embodiments illustrated in the figures. The foregoing description is therefore not to be considered limiting, but rather explanatory. The following claims are to be understood as meaning that a named feature is present in at least one embodiment of the invention. This does not preclude the presence of further features. Insofar as the claims and the foregoing description define 'first' and 'second' features, this designation serves to distinguish between two similar features without establishing any hierarchy. Reference symbol list 1 Axial flux machine 2 Stator 3 Air gap 4 Rotor 5 Housing 6 Housing base 7 Housing cover 8 Positioning device 9 Positioning device 10 Positioning device 11 Recess 12 Component 13 Conductor 14 Bushing 15 Cylindrical ring section 16 Positioning device 17 Positioning device 18 Component 19 Positioning device 20 Stator body 21 Stator yoke 22 Stator teeth 23 Stator winding 24 Cooling channels 25 Cooling fluid 26 Cooling fluid inlet 27 Cooling fluid outlet 28 Sealing ring 29 Retaining ring

Claims

An electric axial flux machine (1), particularly for use within a powertrain of a hybrid or fully electric motor vehicle, comprising a stator (2) and a rotor (4) separated from the stator (2) by an air gap (3), wherein the stator (2) is received in a cup-shaped annular housing (5) with a housing base (6) extending radially in the direction of the rotation, wherein the housing base (6) extends through the air gap (3) between the stator (2) and the rotor (4), and the housing (5) is closed on the side axially opposite the housing base (6) by a housing cover (7), and the housing cover (7) has at least one first positioning means (8) projecting axially out of the housing cover (7) or at least one projecting axially into the housing cover (7), which interacts with a corresponding second positioning means (9) on the stator (2) in such a way thatthat the position of the stator (2) relative to the housing cover (7) is fixed, characterized in that the second positioning means (9) is designed as a recess (11) extending axially into the stator (2). Axial flux machine (1) according to claim 1, characterized in that the housing cover (7) has at least one third positioning means (10) projecting in an axial direction from the housing cover (7) or at least one third positioning means (10) projecting in an axial direction into the housing cover (7), which interacts with a corresponding fourth positioning means (19) on the housing (5) in such a way that the position of the housing (5) relative to the housing cover (7) is determined. Axial flux machine (1) according to claim 2, characterized in that the third positioning means (10) is formed in one piece, in particular monolithically, with the housing cover (7). Axial flux machine (1) according to claim 2, characterized in that the third positioning means (10) is designed as a component (12) separate from the housing cover (7). Axial flux machine (1) according to one of claims 1 to 4, characterized in that the first positioning means (8) is formed in one piece, in particular monolithically, with the housing cover (7). Axial flux machine (1) according to one of claims 1 to 4, characterized in that the first positioning means (8) is designed as a component (12) separate from the housing cover (7). Axial flux machine (1) according to claim 4 or 6, characterized in that the separate component (12) has a feedthrough (14) for at least one electrical conductor (13) from the housing (5). Axial flux machine (1) according to one of claims 1 to 7, characterized in that the housing cover (7) has a cylindrical ring section (15) extending in the axial direction towards the rotor (4) on which at least one fifth positioning means (16) has a radially projecting into or extending out of the cylindrical ring section (15), which cooperates with a corresponding sixth positioning means (17) on the housing (5) in such a way that the position of the housing (5) relative to the housing cover (7) is determined. Axial flux machine (1) according to claim 8, characterized in that the fifth positioning means (16) is formed in one piece, in particular monolithically, with the cylindrical ring section (15). Axial flux machine (1) according to claim 8, characterized in that the fifth positioning means (16) is designed as a component (18) separate from the cylindrical ring section (15). Axial flux machine (1) according to one of claims 1 to 10, characterized in that the axial flux machine (1) is configured in an I-arrangement.

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