Stator assembly, axial flux machine, and method for producing an axial flux machine

Abstract

The invention relates to a stator assembly (1) for an electric axial flux machine (2), comprising a stator (3) and a stator receiving area (4) which is connected to the stator (3). The stator (3) has a disc-shaped stator yoke (5) from which a plurality of stator teeth (6) extend axially, wherein the stator receiving area (4) has rivet bosses (7) which extend outwards from the stator receiving area (4) in the axial direction and each of which engages into an opening (9) that has an undercut (8) and extends axially into the stator yoke (5) and each of which rests against the undercut (8) such that the stator (3) is secured axially as well as radially against the stator receiving area (4) via the formed rivet connections (10).

Description

[0001] Stator arrangement, axial flux machine and method for producing an axial flux machine

[0002] The present invention relates to a stator arrangement for an electric axial flux machine comprising a stator and a stator receptacle connected to the stator, wherein the stator has a disc-shaped stator yoke from which a plurality of stator teeth extend axially.

[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.

[0005] Axial flux machines are also increasingly being used in such electric 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 axial space available 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, another 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.

[0006] The object of the invention is to realize a simple and secure fastening of a stator of an axial flux machine to a stator holder.

[0007] This object is achieved by a stator arrangement for an electrical axial flux machine comprising a stator and a stator receptacle connected to the stator, wherein the stator has a disk-shaped stator yoke from which a plurality of stator teeth extend axially, wherein the stator receptacle has rivet lugs extending in the axial direction from the stator receptacle, which rivet lugs each engage in an opening having an undercut and extending axially into the stator yoke and bear against the undercut, so that the stator is fixed axially and radially to the stator receptacle via the riveted connections formed.

[0008] The advantage of such a stator arrangement for an electric axial flux machine is that the stator can be easily attached to the stator mount. The riveted joints between the stator and the stator mount enable a stable and reliable connection that can withstand both axial and radial loads. When joining the components, the rivet bosses help align them.

[0009] The rivet bosses are preferably formed monolithically with the stator receptacle. Depending on the application, it may be advantageous to design an axial flux machine in an I-arrangement or an H-arrangement. In an I-arrangement, the rotor is arranged axially next to a stator or between two stators. In an H-arrangement, two rotors are arranged on opposite axial sides of a stator. The axial flux machine according to the invention is preferably configured in an I-arrangement.

[0010] In principle, it is also conceivable that the axial flux machine consists of exactly one stator and exactly one rotor.

[0011] 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.

[0012] The stator of the electric axial flux machine according to the invention preferably has a stator body with a plurality of stator windings arranged in the circumferential direction. The stator body can be formed as a single piece or segmented in the circumferential direction. The stator body can be formed from a stator core with a plurality of laminated layers of electrical steel. Alternatively, the stator body can also be formed from a pressed soft magnetic material, such as the so-called SMC (Soft Magnetic Compound).

[0013] 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 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 accommodated in a rotor molded entirely or partially from a plastic.

[0014] A rotor shaft is a rotatably mounted shaft of an electrical machine to which the rotor or rotor body is rotationally fixedly coupled.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] The control device can 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 can comprise one or more electronic memories in which data can be stored in a changeable and / or unchangeable manner. 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 carrying out computing operations for processing data, particularly preferably by means of software. The control units can preferably be networked with one another, thus enabling wired and / or wireless data exchange between control units.In particular, it is also possible to network the control units with each other via bus systems existing in the vehicle, such as CAN bus or LIN bus.

[0019] 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.

[0020] 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.

[0021] 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. 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 of 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 a power output of 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, more preferably greater than 10,000 rpm, and most 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.

[0022] 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.

[0023] 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 drive train in a particularly simple manner. In particular, an axial flux machine and a clutch system can be present. The stator receptacle can be plate-shaped, at least in sections; particularly preferably, the stator receptacle is designed in a shell-like manner, in which a plate-shaped base is enclosed by a rim extending from the base. Most preferably, the stator receptacle is formed from a sheet metal. In principle, it would also be possible to form the stator receptacle from a plastic.

[0024] According to an advantageous embodiment of the invention, at least one of the openings, preferably a plurality of the openings, particularly preferably all openings, each has / have a base from which a dome extends axially in the direction of the rivet boss, engaging a rivet head of the rivet boss. The advantage of this embodiment is that, after the rivet connection has been made, the rivet head of the rivet boss is shaped in such a way that the pressure in the region of the flanks of the mandrel is increased. The mandrel preferably has a V-shaped contour.

[0025] According to a further preferred development of the invention, the stator yoke can also be formed from a plurality of axially stacked stator laminations. The advantage of a stator arrangement in which the stator yoke is formed from a plurality of axially stacked stator laminations is that this leads to higher magnetic efficiency of the machine. By using stacked laminations, losses due to eddy currents and hysteresis can be minimized, as the laminations are able to conduct and distribute the magnetic energy more efficiently. Furthermore, the use of stacked laminations is cost-effective and enables simpler production of the stator arrangement.

[0026] Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the openings and the respective undercuts are formed by punching out the corresponding stator laminations. The advantage of a stator arrangement in which the openings and the respective undercuts are formed by punching out the corresponding stator laminations is, among other things, that this contributes to cost-efficient production. Instead of producing the openings and undercuts separately, they can be punched directly into the stator laminations, saving time and material. Furthermore, this leads to greater accuracy and precision of the stator arrangement, since the punching enables uniform and consistent shaping.

[0027] According to another particularly preferred embodiment of the invention, the stator yoke can be formed from a solid material, and the undercuts of the openings can be formed by an additional sheet metal member attached to the stator yoke. A significant advantage of such a stator arrangement is that, if the stator yoke is formed from a solid material, and the undercuts of the openings are formed by an additional sheet metal member attached to the stator yoke, this results in greater stability and rigidity of the stator yoke. By using a solid material, the stator yoke can have greater mechanical strength, which leads to improved stability of the entire machine. Furthermore, the additional sheet metal member enables easier production of the undercuts, as it can be manufactured separately and then attached to the stator yoke.This simplifies and accelerates the production of the stator assembly, as, for example, the punching of delicate sheet metal contours can be avoided. The additional sheet metal can be firmly attached to the stator yoke using a welding process, particularly laser welding. It is also possible to form cooling channels from the thin sheet metal to cool the stator.

[0028] Furthermore, the invention can also be further developed such that a fluid can flow through the openings during operation of the axial-flow machine. The advantage of this design is that it allows for effective cooling of the machine. Flowing a fluid such as oil, air, or water through the openings enables efficient heat dissipation from the stator yoke area, leading to improved performance and efficiency. Furthermore, this can help extend the service life of the machine by preventing overheating and thermal damage.

[0029] In a likewise preferred embodiment variant of the invention, it can also be provided that the axial flux machine, in particular for a drive train of a motor vehicle, comprises a stator arrangement according to one of claims 1-6.

[0030] The object of the invention can further be achieved by a method for producing a stator arrangement for an electric axial flux machine comprising the following steps:

[0031] - Providing a stator with a disc-shaped stator yoke from which a plurality of stator teeth extend axially and openings extending axially into the stator yoke, each having an undercut,

[0032] - Provision of a stator holder having rivet lugs extending axially from the stator holder,

[0033] - Inserting the rivet lugs into the openings of the stator yoke

[0034] - Forming riveted joints by deforming one of the rivet lugs in the respective associated opening so that the stator is fixed radially and axially in the stator holder.

[0035] According to a further preferred embodiment of the method, it can be provided that a stamping tool is used to form the riveted connections, which stamping tool is placed on the side of the stator receptacle facing away from the opening and is subjected to force in the axial direction, so that at least one of the rivet projections is displaced in the axial direction into the respective opening of the stator yoke and is plastically deformed.

[0036] Finally, the invention can also be advantageously implemented in such a way that the punching tool has a mandrel extending axially therefrom, which can result in an improved formation of the riveted joint. The invention will be explained in more detail below with reference to figures, without limiting the general inventive concept.

[0037] It shows:

[0038] Figure 1 shows an axial flow machine in I-design in a schematic axial section,

[0039] Figure 2 shows a stator arrangement of an axial flow machine in an exploded view,

[0040] Figure 3 shows a stator arrangement of an axial flux machine in a perspective view,

[0041] Figure 4 shows four different designs of a stator arrangement, each in a schematic sectional view,

[0042] Figure 5 shows a first embodiment of a stator arrangement in a view before assembly of the stator holder and formation of the riveted connection and a view after assembly of the stator holder and formation of the riveted connection,

[0043] Figure 6 shows a second embodiment of a stator arrangement in a view before assembly of the stator holder and formation of the riveted connection and a view after assembly of the stator holder and formation of the riveted connection,

[0044] Figure 7 shows a third embodiment of a stator arrangement in a view before assembly of the stator holder and formation of the riveted connection and a view after assembly of the stator holder and formation of the riveted connection, Figure 8 shows a motor vehicle with an electric drive train in a schematic representation.

[0045] Figure 1 shows an axial flux machine 2 in an I-configuration with two axially spaced disc-shaped stators 3, between which the disc-shaped rotor 41 is rotatably mounted on the rotor shaft 42. The stators 3 are fixed to a stator holder 4, which is part of a motor housing of the axial flux machine 2. The axial flux machine 2 can be used in particular for a drive train 43 of a motor vehicle 44, as also outlined in Figure 8.

[0046] Figures 2-3 show a stator arrangement 1 for the electric axial flux machine 2 comprising a stator 3 and a stator receptacle 4 connected to the stator 3, wherein the stator 3 has a disk-shaped stator yoke 5 from which a plurality of stator teeth 6 extend axially.

[0047] The stator receptacle 4 has rivet lugs 7 extending axially from the stator receptacle 4, each of which engages in an opening 9 having an undercut 8 and extending axially into the stator yoke 5, and rests against the undercut 8, so that the stator 3 is fixed axially and radially to the stator receptacle 4 via the riveted connections 10. This can also be clearly seen when viewed in conjunction with Figures 4-7.

[0048] From the illustrations c, d of Figure 4 and Figure 7 it can also be seen that at least one of the openings 9, preferably a plurality of the openings 9, particularly preferably all of the openings 9 each has / have a base 11 from which a dome 12 extends axially in the direction of the rivet boss 7, which dome engages in a rivet head 13 of the rivet boss 7.

[0049] As can also be seen in Figure 4, the stator yoke 5 is formed from a plurality of axially stacked stator laminations 14, wherein the openings 9 and the respective undercuts 8 are formed by punching out the corresponding stator laminations 14.

[0050] Figures 5-7 show embodiments of the stator 3 in which the stator yoke 5 is formed from a solid material. In Figure 7, the undercuts 8 of the openings 9 are formed by an additional sheet 15 attached to the stator yoke 5. Figures 5-7 also show that a fluid can flow through the openings 9 during operation of the axial-flow machine 2, which can particularly improve the cooling of the stator yoke 5 during operation of the axial-flow machine 2.

[0051] The stator assembly 1 for the electric axial flux machine 2 can be manufactured as follows:

[0052] First, a stator 3 is provided with a disk-shaped stator yoke 5, from which a plurality of stator teeth 6 extend axially, and which has openings 9 extending axially into the stator yoke 5, each having an undercut 8. Furthermore, a stator receptacle 4 is provided, which has rivet projections 7 extending axially from the stator receptacle 4.

[0053] Then, the rivet lugs 7 are inserted into the openings 9 of the stator yoke 5 and subsequently the formation of rivet connections 10 takes place by deforming one of the rivet lugs 7 in the respectively assigned opening 9, so that the stator 3 is fixed radially and axially in the stator receptacle 4.

[0054] This can also be clearly seen in Figures 5-7. The rivet projection 7 is thus pressed axially against the bottom 11 of the opening 9 and is plastically deformed to such an extent that it ultimately rests against the undercut 8. In the embodiment of Figure 7 with the additional sheet 15, the undercut 8 formed on the additional sheet 15 can be deflected axially in a resilient manner during the formation of the rivet connection 10 and, after the rivet connection 10 has been created, can spring back to its original position, so that the rivet head 13 does not rest against the bottom 11 of the opening 9. To form the riveted joints 10, a stamping tool 16 is used, which is placed on the side 17 of the stator holder 4 facing away from the opening 9 and is subjected to force in the axial direction, so that at least one of the rivet projections 7 is displaced in the axial direction into the respective opening 9 of the stator yoke 5 and is plastically deformed.The punch tool 16 can have a mandrel 18 extending axially therefrom, resulting in the riveted joint configuration shown in Figure 4 (d). The flanks of the tip of the mandrel 18 can be used to specifically reinforce the hole bearing or the compression.

[0055] The invention is not limited to the embodiments illustrated in the figures. The above description is therefore not to be considered restrictive, but rather explanatory. The following claims are to be understood in such a way that a stated feature is present in at least one embodiment of the invention. This does not exclude the presence of further features. Where the claims and the above description define 'first' and 'second' features, this designation serves to distinguish between two similar features without establishing a priority.

[0056] List of reference symbols

[0057] 1 Stator arrangement

[0058] 2 axial flux machine

[0059] 3 Stator

[0060] 4 Stator holder

[0061] 5 Stator yoke

[0062] 6 stator teeth

[0063] 7 rivet warts

[0064] 8 undercut

[0065] 9 Opening

[0066] 10 riveted joint

[0067] 11 Floor

[0068] 12 Thorn

[0069] 13 rivet head

[0070] 14 stator laminations

[0071] 15 Additional sheet

[0072] 16 stamping tools

[0073] 17 page

[0074] 18 Thorn

[0075] 41 Rotor

[0076] 42 Rotor shaft

[0077] 43 Drivetrain

[0078] 44 Motor vehicle

Claims

Claims 1. Stator arrangement (1) for an electrical axial flux machine (2) comprising a stator (3) and a stator receptacle (4) connected to the stator (3), the stator (3) having a disk-shaped stator yoke (5) from which a plurality of stator teeth (6) extend axially, characterized in that the stator receptacle (4) has rivet lugs (7) extending in the axial direction from the stator receptacle (4), which rivet lugs each engage in an opening (9) having an undercut (8) and extending axially into the stator yoke (5) and bear against the undercut (8), so that the stator (3) is fixed axially and radially to the stator receptacle (4) via the rivet connections (10) formed.

2. Stator arrangement (1) according to claim 1, characterized in that at least one of the openings (9), preferably a plurality of the openings (9), particularly preferably all of the openings (9) each have a base (11) from which a dome (12) extends axially in the direction of the rivet boss (7), which dome engages in a rivet head (13) of the rivet boss (7).

3. Stator arrangement (1) according to claim 1 or 2, characterized in that the stator yoke (5) is formed from a plurality of axially stacked stator laminations (14).

4. Stator arrangement (1) according to claim 3, characterized in that the openings (9) and the respective undercuts (8) are formed by punching out the corresponding stator laminations (14).

5. Stator arrangement (1) according to claim 1 or 2, characterized in that the stator yoke (5) is formed from a solid material and the undercuts (8) of the openings (9) are formed by an additional sheet (15) fastened to the stator yoke (5).

6. Stator arrangement (1) according to one of the preceding claims, characterized in that the openings (9) can be flowed through by a fluid during operation of the axial flow machine (2).

7. Axial flux machine (2), in particular for a drive train () of a motor vehicle (), comprising a stator arrangement (1) according to one of claims 1 -6.

8. A method for producing a stator arrangement (1) for an electric axial flux machine (2) comprising the following steps: - providing a stator (3) with a disc-shaped stator yoke (5) from which a plurality of stator teeth (6) extend axially and which have openings (9) extending axially into the stator yoke (5), each having an undercut (8), - providing a stator holder (4) which has rivet lugs (7) extending in the axial direction from the stator holder (4), Inserting the rivet lugs (7) into the openings (9) of the stator yoke (5) - Forming riveted joints (10) by deforming one of the rivet projections (7) in the respectively associated opening (9), so that the stator (3) is fixed radially and axially in the stator receptacle (4).

9. Method according to claim 8, characterized in that a stamping tool (16) is used to form the riveted joints (10), which is placed on the side (17) of the stator holder (4) facing away from the opening (9) and is subjected to force in the axial direction, so that at least one of the rivet projections (7) is displaced in the axial direction into the respective opening (9) of the stator yoke (5) and is plastically deformed.

10. Method according to claim 9, characterized in that the stamping tool (16) has a mandrel (18) extending axially therefrom.

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