Rotor and method for producing a rotor

Abstract

The invention relates to a rotor (1) for an axial flux machine (2), in particular for an axial flux machine (2) within a drive train (3) of a motor vehicle (4), comprising an inner ring (5) and an outer ring (6) arranged coaxially relative to same, wherein reinforcing struts (7) extending in the radial direction between the inner ring (5) and the outer ring (6) are arranged in the form of spokes, and a respective magnetic element (8) is arranged between two adjacent reinforcing struts (7) in the circumferential direction, wherein, in the circumferential direction on both sides of one of the reinforcing struts, a respective coupling element (9) is arranged between one of the magnetic elements (8) and the corresponding reinforcing strut (7), and wherein the coupling elements (9) are formed from a material that is different from the inner ring (6) and / or the outer ring (6) and / or the magnetic elements (8) and / or the reinforcing struts (7).

Description

[0001] Rotor and method for producing a rotor

[0002] The present invention relates to a rotor for an axial flux machine, in particular for an axial flux machine within a drive train of a motor vehicle, comprising an inner ring and an outer ring arranged coaxially thereto. Reinforcing struts extending radially between the inner ring and the outer ring are arranged in a spoke-like manner, and a magnetic element is arranged between each of two circumferentially adjacent reinforcing struts. The invention further relates to methods for producing a rotor.

[0003] Electric motors are increasingly being used to power motor vehicles, creating alternatives and complements 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, Volume 113, May 2011, pages 360-365, by Erik Schneider, Frank Fickl, Bernd Cebulski, and Jens Liebold, entitled "Highly Integrative and Flexible Electric Drive Unit for E-Vehicles," which arguably represents the closest state of the art. This article describes a drive unit for a vehicle axle that includes an electric motor arranged coaxially with a bevel gear differential. Such drive units are also referred to as e-axles or electrically operated drivetrains.

[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, a further advantage of the axial flux machine is its comparatively high torque density. This is due to the larger air gap area and the longer lever arm available in a given 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] Due to its disc-shaped main components, an axial flux machine is particularly well-suited for applications where a very short electric motor length is essential and where a relatively large motor diameter is still acceptable. When developing such axial flux machines, it is therefore generally advisable to strive for the shortest possible design, while keeping the outer diameter of the axial flux machine no larger than absolutely necessary. Axial flux machines for automotive applications also always have to meet the requirements of low weight, high power density, and low cost.

[0007] The disc-shaped rotor's task, among other things, is to transfer the force transmitted to the rotor's magnets to the rotor shaft. In addition to the circumferential direction, the magnets must be held in place both radially and axially between the stator and the rotor shaft.

[0008] Centrifugal force and the outward-moving components result in unfavorable, circumferential tensile stresses between and within the rotor components. Therefore, the object of the invention is to provide a rotor for an electric axial flux machine that is cost-effective to manufacture and easy to assemble, as well as allowing for good adjustability of the rotor's circumferential stiffness. Furthermore, the object of the invention is to implement an improved method for manufacturing a rotor.

[0009] This object is achieved by a rotor for an axial flux machine, in particular for an axial flux machine within a drive train of a motor vehicle, comprising an inner ring and an outer ring arranged coaxially thereto, wherein stiffening struts extending in the radial direction between the inner ring and the outer ring are arranged in a spoke-like manner, and a magnetic element is arranged between each two stiffening struts adjacent in the circumferential direction, wherein a coupling element is arranged on both sides of one of the stiffening struts in the circumferential direction between one of the magnetic elements and the corresponding stiffening strut, wherein the coupling elements are formed from a material different from the inner ring and / or the outer ring and / or the magnetic elements and / or the stiffening struts.

[0010] This provides the advantage that the rotor components (stiffening struts, magnetic elements, inner ring, outer ring) can be connected to one another circumferentially via the coupling elements. By appropriately designing the material and geometry of the coupling elements, they can be adjusted so that they can tolerate both relative displacements and carry out load transfers. In this case, the coupling elements can simultaneously relieve the load on their contact surfaces, particularly due to their preferred elasticity. Furthermore, it is also possible, for example, to specifically adjust the circumferential stiffness of the rotor (particularly in areas within the bandage) via the Young's modulus of the coupling elements in the disc plane and the geometry of the coupling elements.

[0011] Despite the extensive connection, the coupling elements allow for relative displacement between the components, keeping contact stresses between the components to a minimum. Furthermore, the coupling elements support the transfer of the magnetic loads (due to centrifugal force) that occur during rotor operation to the stiffening elements.

[0012] The coupling elements can be produced, for example, by injection molding or encapsulation with filled, reinforced, or unreinforced polymer. They can also be realized using an adhesive. Furthermore, it is possible for the coupling elements to be produced directly in the primary molding process and subsequently bonded, for example, via an adhesive bond. First, the individual elements of the claimed subject matter of the invention are explained in the order in which they appear in the set of claims, followed by a description of particularly preferred embodiments of the subject matter of the invention.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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 electrical 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).

[0017] The stator is housed in a housing. The housing can be a single-piece or multi-piece construction. The housing is particularly preferably made of plastic. The housing can be closed on all sides. It is also possible to provide openings in the housing, for example, to reduce weight or to provide access to a component.

[0018] The magnetic elements can be designed, for example, as permanent magnets. Preferably, the magnetic elements are designed essentially identically.

[0019] A rotor shaft is a rotatably mounted shaft of an electrical machine to which the rotor or rotor body is rotationally fixedly coupled.

[0020] 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.

[0021] 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 30 kW, preferably greater than 50 kW, and in particular greater than 70 kW. It is further preferred that the electric machine provides speeds greater than 5,000 rpm, particularly preferably greater than 10,000 rpm, and most particularly preferably greater than 12,500 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. 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 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] Magnetic element

[0024] A magnetic element preferably has a longitudinal extension and has a circumferential contour, wherein on a first side, which faces a first direction of rotation of the rotor when the magnetic element is installed in the rotor, a longitudinally extending first planar surface section and a longitudinally extending second planar or freely formed surface section are formed, wherein when the magnetic element is installed in the rotor, the first surface section is positioned radially above the second surface section, and on a second side, which faces a second direction of rotation of the rotor when the magnetic element is installed in the rotor, a longitudinally extending third planar surface section and a longitudinally extending fourth planar or freely formed surface section are formed.

[0025] Preferably, when the magnetic element is installed in the rotor, the third surface section is positioned radially above the fourth surface section, wherein a first plane extending through the first surface section and a third plane extending through the third surface section intersect radially above the magnetic element in the direction of the longitudinal extent when the magnetic element is installed in the rotor, and a second plane extending through the second surface section and a fourth plane extending through the fourth surface section intersect radially below the magnetic element in the direction of the longitudinal extent when the magnetic element is installed in the rotor.

[0026] This provides the advantage that, particularly via the first flat surface section and the third flat surface section, a straight and flat, precisely and economically producible surface can be provided in a partial area of ​​the circumferential contour of the magnetic element, which can be well sealed in an injection molding or bonding process to form the rotor. Furthermore, the first flat surface section and the third flat surface section allow for particularly precise radial positioning of the magnetic elements.

[0027] Furthermore, a "center of mass to contact surface" relationship of the magnetic element can be established via the first flat surface section and the third flat surface section. They can thus be used as a reference when sorting or assigning the magnetic elements based on their center of mass position. This allows for geometric balancing or, through geometric sorting, minimizing the rotor's imbalance.

[0028] Sorting and / or arranging the magnetic elements to reduce imbalance can be performed in addition to, or in combination with, a weight analysis of the magnetic elements. This optimizes the positioning accuracy of the magnetic elements to minimize imbalance caused by uneven positioning of the sorted magnetic elements in the rotor. The accuracy of the rotor's balance—influenced by the magnetic elements—is thus optimized by sorting the magnets, taking geometric and mass deviations into account, and assigning them to a specific position in the rotor.

[0029] The first flat surface section and the third flat surface section provide areas along the circumferential magnet contour that are geometrically simplified (flat, straight surface sections) and can therefore be manufactured inexpensively and precisely. As already mentioned above, they can also be used as sealing surfaces during production.

[0030] Because a first plane extending through the first surface section and a third plane extending through the third surface section intersect radially above the magnetic element in the direction of the longitudinal extent when the magnetic element is installed in the rotor, the first flat surface section and the third flat surface section have contact lines which take a closing direction towards the outside and can thus be used as a positioning option for the magnetic element in rotor production.

[0031] The circumferential contour of the magnetic elements can be implemented, for example, directly in a sintering tool, on the individual discs of a layered magnetic element, or on the entire magnet. The geometric features of the circumferential contour can be formed before passivation or after passivation with additional passivation or subsequent processes with a passivating effect. They can be applied to both segmented and complete magnets. The geometric details of the circumferential contour can be implemented symmetrically or asymmetrically and / or in sections on or within the circumferential contour.

[0032] For the purposes of this invention, a flat surface segment is a flat, two-dimensional surface. This means that for every two points in a surface segment, a straight line runs entirely within the surface segment. The surface segment itself may also exhibit local unevenness, in which case an averaged plane is placed through the corresponding surface segment.

[0033] The magnetic elements can be designed, for example, as permanent magnets. Preferably, the magnetic elements are designed essentially identically.

[0034] According to an advantageous embodiment of the invention, the magnetic element can be formed mirror-symmetrically with respect to its longitudinal extent. The advantage of this embodiment is that the

[0035] Ease of assembly and balancing of the rotor can be improved.

[0036] According to a further preferred development of the invention, the circumferential contour can also be provided, at least in sections, with a chamfer formed at the transition between the circumferential contour and an axial surface. By providing a contour at the transition from the axial to the circumferential magnetic area, adhesive joints in these areas can, for example, be relieved of stress or their load-bearing capacity can be increased.

[0037] The chamfer also allows for a more elastic connection to an injection-molded or adhesive surface.

[0038] Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the first flat surface section and / or the second flat or freely formed surface section and / or the third flat surface section and / or the fourth flat or freely formed surface section each have structures that protrude from or into the respective flat surface, at least in sections. This also makes it possible, in particular, to provide macroscopic shape details on one or more surface sections of the magnetic element, which improve the transfer of (centrifugal) forces to the corresponding adhesive surfaces and / or directly molded areas when the magnetic element is installed.

[0039] According to another particularly preferred embodiment of the invention, the circumferential contour can have a fifth surface section which, when installed in the rotor, is oriented radially outward and connects the first surface section to the third surface section, wherein the fifth surface section has a circular arc-shaped contour whose axis of rotation runs coaxially with a rotational axis of the rotor. By specifying the circular arc-shaped, radially outer contour, a homogeneous (centrifugal force) load transfer to the supporting components, such as the auxiliary bandage or load bandage, of the rotor can be enabled for unlayered and layered magnetic elements.Furthermore, the invention can also be further developed such that the circumferential contour has a sixth surface section, which, when installed in the rotor, is oriented radially inward and connects the second surface section to the fourth surface section, wherein the sixth surface section has a chamfer formed at the transition between the sixth surface section and an axial surface. This allows a wedge-like shape of the sixth surface section, which can, for example, improve the connection to an inner ring of the rotor.

[0040] In principle, it is possible for a magnetic element to be positioned via contact surfaces, but also via contact points.

[0041] In a likewise preferred embodiment of the invention, the magnetic element can also have an upper region and a lower region, wherein the upper region extends above half of the longitudinal extent of the magnetic element and the lower region extends below half of the longitudinal extent of the magnetic element, and the first surface section and the third surface section extend exclusively within the upper region of the magnetic element. This allows for balancing or a defined contact of the magnetic element in the rotor through the upper region of the magnetic element.

[0042] Furthermore, it is also conceivable that balancing of the rotor is realized through the lower area.

[0043] It may also be advantageous to further develop the invention in such a way that the magnetic element is layered or monolithically formed.

[0044] It is further preferred that in the circumferential direction on both sides of one of the stiffening struts a coupling element is arranged between one of the magnetic elements and the corresponding stiffening strut, wherein the coupling elements are formed from a material different from the inner ring and / or the outer ring and / or the magnetic elements and / or the stiffening struts.

[0045] In principle, it would also be conceivable that at least one coupling element is arranged between two magnetic elements adjacent in the circumferential direction, which coupling element is coupled to at least one of the magnetic elements in a force-transmitting manner in the radial direction.

[0046] According to an advantageous embodiment of the invention, the coupling elements can be formed from a material with a modulus of elasticity between 400 MPa and 46,000 MPa. The advantage of this embodiment is that it provides a sufficient stiffness difference to the rotor magnets, thereby achieving particularly good coupling properties.

[0047] According to a further preferred development of the invention, the coupling elements can also be formed from a material that exhibits elastic behavior during operation of the rotor. This can relieve the contact surfaces of the coupling elements with the adjacent components.

[0048] Furthermore, according to a similarly advantageous embodiment of the invention, the coupling elements can be rod-shaped and have an average thickness of at least 0.4 mm, preferably 0.4-2 mm, particularly preferably 0.5-1.5 mm, in the circumferential direction. The advantageous effect of this embodiment is that it allows a minimum elasticity for decoupling to be achieved.

[0049] According to another particularly preferred embodiment of the invention, the coupling elements may have at least one connecting section that deviates from a rod shape and that rests at least partially against one of the magnetic elements. This can achieve, in particular, the effect that radially acting force components between the coupling elements and the magnetic elements are better transmitted, for example, by the magnetic elements being positively encompassed by the corresponding connecting sections of the coupling elements.

[0050] Furthermore, the invention can also be further developed in such a way that the coupling elements are designed to be essentially identical, which can also have a positive influence on the manufacturing costs due to the higher degree of uniformity.

[0051] In a likewise preferred embodiment of the invention, the stiffening struts can also be cuboid-shaped, with the coupling elements each abutting at least partially against a longitudinal surface of one of the stiffening struts. This ensures that the load is transferred homogeneously from one of the stiffening elements to one of the coupling elements without local elevations.

[0052] The rotor can be manufactured by a method for manufacturing a rotor for an axial flux machine, in particular for an axial flux machine within a drive train of a motor vehicle, comprising the following steps:

[0053] - Provision of a mold,

[0054] - Provision of a plurality of stiffening struts,

[0055] - Providing a plurality of magnetic elements,

[0056] - Arrangement of the stiffening struts and the magnetic elements in the molding tool, so that the stiffening struts are positioned in a spoke-like manner and a magnetic element is arranged between each of two circumferentially adjacent stiffening struts, and wherein an air space is provided on both sides of each of the stiffening struts between one of the magnetic elements and the corresponding stiffening strut in the molding tool,

[0057] Injection molding of an inner ring and an outer ring using the

[0058] Forming tool, so that the position of the stiffening struts, the magnetic elements, the inner ring and the outer ring relative to each other is fixed,

[0059] - Filling the air spaces on both sides of one of the stiffening struts with a material that is different from the material of the inner ring and / or the outer ring and / or the magnetic elements and / or the stiffening struts, so that a coupling element is formed between one of the magnetic elements and the corresponding stiffening strut.

[0060] Alternatively, a rotor can also be manufactured by a method for producing a rotor for an axial flow machine, in particular for an axial flow machine within a drive train of a motor vehicle, comprising the following steps:

[0061] - Provision of a mold,

[0062] - Provision of a plurality of stiffening struts,

[0063] - Providing a plurality of magnetic elements,

[0064] - Providing a plurality of coupling elements with a material that is different from the material of an inner ring and / or an outer ring and / or the magnetic elements and / or the stiffening struts,

[0065] - Arrangement of the stiffening struts and the magnetic elements in the molding tool, so that the stiffening struts are positioned in a spoke-like manner and a magnetic element is arranged between each of two circumferentially adjacent stiffening struts, and wherein an air space is provided on both sides of each of the stiffening struts between one of the magnetic elements and the corresponding stiffening strut in the molding tool,

[0066] - Injection molding of the inner ring and the outer ring using the mold so that the position of the stiffening struts, the magnetic elements, the inner ring and the outer ring relative to each other is determined, insertion of the coupling elements into the air spaces on both sides of one of the stiffening struts

[0067] The coupling elements can optionally also be connected to adjacent component structures

[0068] According to a further preferred embodiment of the invention, the rotor can have an inner ring and an outer ring arranged coaxially thereto, wherein stiffening struts extending in the radial direction between the inner ring and the outer ring are arranged in a spoke-like manner, and a magnetic element is arranged between each of two stiffening struts adjacent in the circumferential direction, wherein an annular bandage element rests on the outer ring by means of a press fit, so that a prestress is introduced into the rotor via the bandage element.

[0069] The bandage element can be manufactured, for example, using a machining process. It is also conceivable for a bandage element to be entirely or partially pressed, wound, or laid. The bandage element can also be entirely or partially injection-molded or cast. Furthermore, the bandage element can be formed using a wet-winding process or a prepreg.

[0070] Preferably, a bandage element has a circumferentially closed contour. Particularly preferably, the bandage element has a polygonal cross-sectional contour that deviates from a circular path on its inner circumferential surface facing the outer ring.

[0071] Most preferably, the auxiliary bandage of the bandage element has a polygonal cross-sectional contour that deviates from a circular path on its inner surface facing the outer ring. It is also preferred that the auxiliary bandage of the bandage element has a polygonal cross-sectional contour that deviates from a circular path on its outer surface facing away from the outer ring. Preferably, the polygonal cross-sectional contour on the outer surface essentially corresponds to the polygonal cross-sectional contour of the inner surface of the auxiliary bandage. Analogously, the load bandage of the bandage element also preferably has a polygonal cross-sectional contour that deviates from a circular path on its inner surface facing the auxiliary bandage.

[0072] A bandage element can be formed, at least in sections, from a plastic material. It is particularly preferred that the plastic be arranged on the bandage element in a continuous, closed manner. Reinforced plastics, in particular fiber-reinforced plastics, are particularly preferred. A fiber-reinforced plastic can contain short fibers, long fibers, or continuous fibers, as well as a mixture thereof. It is also conceivable that a bandage element is made, at least in sections, and preferably in a continuous, closed manner, from a metallic material, in particular steel, and / or a ceramic.

[0073] A bandage element can be made of several parts with the same or partially different materials, whereby preferably at least one material in the circumferential direction of the bandage must have an E-modulus >48000MPa.

[0074] A bandage element can be formed directly onto the outer ring of the rotor in a primary forming process or can be attached to it subsequently, after the outer ring has been formed.

[0075] It is also conceivable that a bandage element is machined at least in some areas before being attached to the outer ring and also afterwards.

[0076] The bandage element can cover the outer ring of the rotor completely or partially in the axial direction. In this case, the most complete axial coverage possible is preferred, as this enables a particularly high and uniform pressure application. In particular, it can be advantageous to arrange several bandage elements axially one behind the other on the rotor, which has the advantage of allowing the bandage element to be constructed modularly and flexibly adapted to the length of a rotor.

[0077] It may also be advantageous to further develop the invention in such a way that an annular auxiliary bandage is applied to the outer ring. The coupling elements, together with the prestressed auxiliary bandage, allow the rotor disk to be subjected to circumferential compression. This can shift the mean stresses of the stress amplitudes toward compression during operation, which in turn has a positive effect on durability.

[0078] According to an advantageous embodiment of the invention, the bandage element can be designed in several parts, with at least one annular auxiliary bandage resting on the outer ring and at least one annular load bandage resting on the auxiliary bandage. The advantage of this design is that it allows for better and more precise control of the preloads applied to the rotor and the operating stresses in the rotor and the bandage.

[0079] According to a further preferred development of the invention, it can also be provided that the material of the auxiliary bandage is different from the material of the load bandage, thereby further optimizing the adjustability of the preloads and the operating stresses in the rotor and the bandage. This means that, for example, magnets and radial struts at least partially determine the deflection points of the polygonal line, thereby increasing the initial stiffness of the installed bandage.

[0080] Furthermore, according to a similarly advantageous embodiment of the invention, at least one material of a multi-part bandage element, in particular the load bandage, can have a modulus of elasticity of >48,000 MPa in the circumferential direction of the bandage element. The advantageous effect of this embodiment is that the bandage can absorb a relevant operating load due to the increased circumferential stiffness, thus reducing the stress on the rotor disk.

[0081] According to another particularly preferred embodiment of the invention, the preload introduced into the rotor by the auxiliary bandage can be greater than the preload introduced by the load bandage. This allows the ratio of mean stress to stress amplitudes in the bandages to be specifically controlled, particularly when using different materials. Likewise, the press-on force can be optimized in relation to the tolerance situation.

[0082] Furthermore, the invention can also be further developed such that the load bandage rests against the auxiliary bandage in such a way that it does not impose any preload on the rotor. The advantage of this design is that the mean stress in the load bandage is minimized.

[0083] In a likewise preferred embodiment variant of the invention, it can also be provided that the outer ring has a polygonal circumferential outer contour with a plurality of support points.

[0084] In this context, it is particularly preferred that the support points of the polygonal profile be determined by the load-introducing elements. This allows, for example, the magnets and radial struts to at least partially determine the deflection points of the polygonal profile, thereby increasing the initial stiffness of the installed bandage.

[0085] If the centrifugal load of the magnets is introduced relatively discretely into a cylindrical or nearly cylindrical bandage element, such a bandage element can only offer low rigidity in the first load range. The first load range is a load area caused, for example, by centrifugal force or thermal expansion during rotor operation. This, in turn, results in large movement amplitudes between the components with corresponding load amplitudes. If the bandage element is polygonalized along its load introduction and support points, it can exhibit advantageous rigidity and absorb corresponding loads particularly well.

[0086] It may also be advantageous to further develop the invention in such a way that the bandage element is formed integrally, in particular monolithically, with the outer ring. This has the advantage that the load-bearing bandage moves even closer to the load-generating components (magnets) and can thus absorb the load more effectively. Likewise, less rigid load transfer paths are reduced, resulting in a more rigid connection with fewer relative movements.

[0087] The rotor can be manufactured, for example, by a process comprising the following steps:

[0088] • Providing a rotor with an inner ring, wherein stiffening struts extending radially outwards from the inner ring are arranged in the rotor in a spoke-like manner, and a magnetic element is arranged between each of two stiffening struts adjacent in the circumferential direction,

[0089] • Arrangement of an annular bandage element on the outer contour of the rotor by means of a press fit, so that a preload is introduced into the rotor via the bandage element,

[0090] • Coupling the rotor to a rotor shaft.

[0091] The method can also be adapted to provide a rotor with an inner ring and an outer ring arranged coaxially thereto, wherein stiffening struts extending in the radial direction between the inner ring and the outer ring are arranged in a spoke-like manner, and a magnetic element is arranged between each of two stiffening struts adjacent in the circumferential direction.

[0092] Furthermore, in a further process step, the inner ring can be partially or completely removed from the rotor, for example by milling.

[0093] Cover plate

[0094] According to an advantageous embodiment of the invention, it can be provided that at least one of the stiffening struts and / or at least one of the magnetic elements is connected to at least one cover plate, which at least partially spans the rotor on a second end face of the rotor, so that during operation of the rotor, force can be transmitted from one of the stiffening struts and / or at least one of the magnetic elements to the at least one cover plate and / or vice versa. This can further improve the axial stiffness, the distribution of stress peaks, the acoustic properties and the wear resistance by covering the rotor at least partially on each of its two end faces by a cover plate.

[0095] According to a further preferred development of the invention, it can also be provided that the cover disk on the first end face of the rotor and / or the cover disk on the second end face of the rotor are / is designed in the shape of an annular disk, which has proven to be particularly advantageous in terms of manufacturing costs and for reasons of operational reliability.

[0096] According to an advantageous embodiment of the invention, it can be provided that the cover disk on the first end face of the rotor and / or the cover disk on the second end face of the rotor is / are formed in multiple parts. In particular, it is conceivable that the cover disk on the first end face of the rotor and / or the cover disk on the second end face of the rotor is / are formed from layered, stacked disk elements. The stacked disk elements can be made of the same or different materials. In addition to a layered, axially multi-part structure, it is also possible for the cover disk on the first end face of the rotor and / or the cover disk on the second end face of the rotor to be formed in multiple parts in the circumferential direction, for example as ring segments.In principle, it may also be advantageous for the cover disk on the first end face of the rotor and / or the cover disk on the second end face of the rotor to be designed in multiple parts in the radial direction, for example as annular disks arranged coaxially to one another.

[0097] It may further be preferred that the cover plate on the first end face of the rotor and the cover plate on the second end face of the rotor each comprise a ferromagnetic material in an overlap region and / or contact region with a magnetic element.

[0098] It is also possible for the cover plate on the first end face of the rotor and the cover plate on the second end face of the rotor to partially cover, completely cover or even protrude from a respective end face.

[0099] In principle, the cover plate on the first end face of the rotor and / or the cover plate on the second end face of the rotor can be designed to be flat or contoured.

[0100] It may also be advantageous for the cover plate on the first end face of the rotor and / or the cover plate on the second end face of the rotor to be surface-treated at least in sections, preferably completely, on their surface facing away from and / or toward the rotor, thereby enabling further modification and adaptation of a cover plate to specific operating conditions of the rotor. In this context, it is also possible for the cover plate on the first end face of the rotor and the cover plate on the second end face of the rotor to be coated at least in sections, preferably completely, on their surface facing away from and / or toward the rotor, for example with a lacquer.In particular, it is also conceivable to design the cover plate on the first end face of the rotor and / or the cover plate on the second end face of the rotor as a single piece with one or more other components of the rotor, for example, with the outer ring and / or the bandage element. Thus, the cover plate on the first end face of the rotor and the cover plate on the second end face of the rotor can be attached directly to these components during the primary forming process or can be attached subsequently.

[0101] The cover plate on the first end face of the rotor and / or the cover plate on the second end face of the rotor can, in particular, also be reworked at least in partial areas after assembly on the rotor, in particular by means of machining processes.

[0102] Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the cover plate on the first end face of the rotor and / or the cover plate on the second end face of the rotor are / is formed from a plastic, in particular a fiber-reinforced and / or spherically reinforced plastic, non-magnetic steel, aluminum or a ceramic.

[0103] According to another particularly preferred embodiment of the invention, the cover disk on the first end face of the rotor and the cover disk on the second end face of the rotor can protrude radially beyond the edge of the outer ring, and a bandage element can be axially supported on the outer ring between the cover disks. This allows the cover disks to function as a receiving and guiding element for the bandage element during its assembly on the rotor and during operation of the rotor.

[0104] Furthermore, the invention can also be further developed such that the cover plate on the first end face of the rotor and / or the cover plate on the second end face of the rotor have fastening means by means of which a torque can be transmitted from the rotor to a rotor flange, via which the torque can be introduced into a rotor shaft. In a likewise preferred embodiment of the invention, it can also be provided that the fastening means comprise fastening openings arranged equidistantly on a circular path. This makes it possible to produce a preferred connection to a flange, wherein the fastening openings are then penetrated, for example, by screws which connect the flange to the rotor in a torque-transmitting manner.

[0105] It may also be advantageous to further develop the invention such that the cover plate on the first end face of the rotor and / or the cover plate on the second end face of the rotor has / has indentations directed into the interior of the rotor. The advantage of these indentations is, in particular, the local conduction and relief of stresses by a cover plate.

[0106] According to a further preferred embodiment of the subject matter of the invention, it can be provided that the cover plate on the first end face of the rotor and / or the cover plate on the second end face of the rotor has / has an average axial extent which corresponds to between 1-80% of the axial extent of the magnetic elements, which has proven to be particularly advantageous with regard to the desirable axial rigidity of a rotor.

[0107] Finally, the invention can also be advantageously designed such that the cover plate on the first end face of the rotor and the cover plate on the second end face of the rotor are substantially identical, which can have a positive influence on the manufacturing costs of the rotor due to the increased proportion of identical parts.

[0108] Furthermore, however, it is also possible for the cover plate on the first end face of the rotor and the cover plate on the second end face of the rotor to be made of different materials and / or to have a different geometric design.

[0109] The cover plate on the first end face of the rotor and / or the cover plate on the second end face of the rotor can be specifically designed with fire protection requirements in mind, thus serving as a protective layer for the other components of the rotor. This allows, for example, the overall fire protection qualification of the rotor to be ensured without the individual components concealed beneath the cover plates having to directly meet these requirements.

[0110] According to a further preferred embodiment of the invention, the rotor for an axial flux machine, in particular for an axial flux machine within a drive train of a motor vehicle, has a plurality of magnetic elements which are arranged circumferentially distributed in the rotor, wherein the magnetic elements are supported radially inwardly on an inner ring.

[0111] The inner ring can also be formed, for example, by a rotor shaft, so that the magnetic elements are supported radially inwards on the rotor shaft, which acts as the inner ring.

[0112] Furthermore, it is possible for the magnetic elements to be supported radially directly on the inner ring, at least in sections, or indirectly, at least in sections, for example, via a contact rib formed radially between the inner ring and a magnetic element. The contact rib can, in particular, be formed integrally with the inner ring.

[0113] This has the advantage that the already partially assembled components of the rotor can be handled together via the inner ring during the manufacturing process.

[0114] The inner surface of the inner ring can be used for repeated machining processes, for example by coupling a corresponding handling tool to the inner surface of the inner ring.

[0115] The inner ring can also help minimize the resistance to circumferential preloading of the rotor by external preloading, allowing the preload to generate circumferential residual stresses. The inner ring thus represents a less rigid inner contour, which allows circumferential preloading of the rotor, for example, by a bandage element, or allows the formation of circumferential residual stresses due to the preload.

[0116] The inner ring also allows for an increase in the individual tolerances of as many of the rotor's other components as possible. The inner ring can "buffer" component tolerances within it. For example, after the stiffness-determining components have been installed together in the rotor, but before the shaft is pressed in, it is possible to adjust the inner diameter of the rotor or inner ring to a common target dimension. The inner ring can thus also define the rotor's inner diameter very precisely.

[0117] The inner ring can be connected to other components of the rotor as a separate component or can be manufactured as a common component with them.

[0118] The inner ring can be machined, pressed, injection-molded, or potted with filled or unfilled, reinforced or unreinforced polymer. It can be attached directly to the support ribs and / or stiffening struts using a primary forming process, or it can be subsequently attached to them. It can also be cut from an extruded profile and bonded to the rotor.

[0119] It is advantageous that the inner circumferential surface of the inner ring has a contour and / or a form-locking means, by means of which a circumferentially defined reception of the rotor can be ensured, for example in a handling tool.

[0120] According to an advantageous embodiment of the invention, it can be provided that the rotor has an outer ring arranged coaxially to the inner ring, on which outer ring the magnetic elements are supported radially outwards. According to a further preferred development of the invention, it can also be provided that a plurality of contact ribs each extend radially outwards from the inner ring and that a plurality of the magnetic elements are supported on the contact ribs. This can ensure that the magnetic elements can rest fixedly against the contact ribs in the radial and / or axial and / or circumferential direction. For this purpose, a contact rib on the contact surface with the magnetic element can have a corresponding contour.

[0121] It is preferred that a contact rib has a V-shaped contour in cross section, wherein the tip of the V-shaped contour is oriented radially inwards.

[0122] Furthermore, according to a similarly advantageous embodiment of the invention, the number of support ribs can be provided to correspond to the number of magnetic elements. The advantageous effect of this embodiment is that it allows for particularly precisely adjustable support of the magnetic elements.

[0123] According to another particularly preferred embodiment of the invention, a plurality of the contact ribs may have an opening extending axially through the respective contact rib. This allows a contact rib to be connected, for example, to a rotor flange in order to transmit torque from the rotor to the rotor flange via the contact ribs.

[0124] Furthermore, the invention can also be further developed in such a way that a stiffening strut extending radially between the inner ring and the outer ring is arranged between two circumferentially adjacent support ribs. The advantage of this design is that it allows for better compensation of the vibration behavior occurring during rotor operation caused by the rotor components subjected to centrifugal force.

[0125] In a likewise preferred embodiment of the invention, it can also be provided that the inner ring and the contact ribs are formed integrally, in particular monolithically, with one another. This allows for simplified production of the inner ring and the contact ribs. According to a further preferred embodiment of the subject matter of the invention, it can therefore also be provided that the inner ring is formed by means of an extrusion process.

[0126] It may also be advantageous to further develop the invention such that the inner ring is made of a material with a Young's modulus of less than 47 GPa. The advantage of this is that the circumferential preload builds up in the structure of the rotor disk and is less blocked by the ring.

[0127] It is further preferred that the axial extent of the inner ring corresponds to at least 20% of the axial extent of the rotor.

[0128] Finally, the invention can also be advantageously designed such that the inner ring is removable from the rotor. The inner ring can thus be removed, for example, before the rotor shaft is pressed in. It is therefore particularly preferred that the contact ribs remain in the rotor when the inner ring is removed.

[0129] In principle, it is of course also possible for the inner ring to serve as a kind of protective element for the radially outer components, for example for the end faces of the stiffening struts towards the rotor shaft.

[0130] In this case, the inner ring can preferably be designed with some clearance relative to the rotor shaft. In particular, the inner ring does not transmit any torque to the rotor shaft via its inner surface.

[0131] Preferably, the rotor for an axial flux machine, in particular for an axial flux machine within a drive train of a motor vehicle, can comprise a plurality of magnetic elements arranged circumferentially distributed within the rotor, wherein the magnetic elements are supported radially inwardly on a plurality of contact ribs. This provides the advantage that the torque generated at the magnetic elements can be transmitted at least partially to a rotor shaft via the contact ribs.

[0132] For this purpose, the torque generated by the magnetic elements is directed to the contact ribs, via which it can then be transmitted to the rotor shaft, for example, via a rotor flange. It is also possible to transmit part of the torque to the rotor shaft via the contact ribs directly or via an inner ring (radially). This can be achieved, for example, by frictional engagement, form fit, and / or material bond. The contact ribs can also transmit the torque to a component or a chain of components, which then transmit the torque to the shaft.

[0133] Furthermore, the contact ribs provide a supporting effect to prevent axial tilting of the magnetic elements during rotor operation. This can also ensure that the magnetic elements are fixed to the contact ribs in the radial, axial, and / or circumferential directions. For this purpose, a contact rib on the contact surface with the magnetic element can have a corresponding contour.

[0134] Furthermore, the support ribs within the rotor support the formation of a predominantly compressive load path from the rotor shaft to the magnetic elements and finally to a bandage element. This allows, in particular, the stress amplitudes along this path to be minimized.

[0135] It is preferred that a contact rib has a V-shaped contour in cross section, wherein the tip of the V-shaped contour is oriented radially inwards.

[0136] A support rib can be designed in one piece or in multiple pieces. A support rib is preferably designed so that it has a radial extension that corresponds to at least 48% of the radial extension between the radially outer edge of the rotor shaft and the radially outer edge of the magnetic elements.

[0137] A contact rib can be connected to other components of the rotor. A contact rib can be present as a separate component within the rotor. It is also possible for several contact ribs, preferably all contact ribs, to be connected to one another, for example, via an inner ring.

[0138] A support rib can be machined, pressed, injection-molded, or potted, with filled or unfilled, reinforced or unreinforced polymer. It can also be made of non-magnetic steel or ceramic.

[0139] A locating rib can be attached directly to a magnetic element and / or the rotor shaft using a primary forming process, or it can be added subsequently. Furthermore, a locating rib can be connected to a single- or multi-layer interface on both the shaft and magnet sides.

[0140] According to an advantageous embodiment of the invention, it can be provided that the number of magnetic elements corresponds to the number of contact ribs, which can contribute to a particularly good support of the magnetic elements.

[0141] In principle, however, it is also conceivable that one mounting rib is provided for the installation of several magnetic elements or that several mounting ribs are used per magnet.

[0142] According to a further preferred development of the invention, it can also be provided that a plurality of the contact ribs have an opening that axially penetrates the respective contact rib. This allows a contact rib to be connected, for example, to a rotor flange in order to transmit torque from the rotor to the rotor flange via the contact ribs. Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that at least one stiffening strut extending in the radial direction is arranged between each two contact ribs that are adjacent in the circumferential direction. The advantage of this embodiment is that it allows the vibration behavior occurring during operation of the rotor to be better compensated by the rotor components subjected to centrifugal force.

[0143] According to a further particularly preferred embodiment of the invention, it can be provided that a plurality of contact ribs each extend radially outward from an inner ring. In this way, the inner ring can contribute to offering as little resistance as possible to circumferential preloading of the rotor by external preloading, so that the preload can generate circumferential residual stresses. The inner ring thus represents a less rigid inner contour, which allows preloading of the rotor in the circumferential direction, for example by a bandage element, or allows the formation of circumferential residual stresses due to the preload. Furthermore, the inner circumferential surface of the inner ring can be used for repeated machining processes, for example by coupling a corresponding handling tool to the inner circumferential surface of the inner ring.

[0144] Furthermore, the invention can also be further developed such that a plurality of contact ribs, preferably all contact ribs, are essentially identical. This increased degree of uniformity of the rotor can, in particular, reduce manufacturing costs.

[0145] In a likewise preferred embodiment of the invention, it can also be provided that a plurality of the contact ribs are formed from a plastic, in particular a fiber-reinforced plastic, a non-magnetic steel or a ceramic.

[0146] It may also be advantageous to further develop the invention in such a way that the contact ribs are formed from an extruded profile. This allows for simplified production of the contact ribs and any inner ring present.

[0147] According to a further preferred embodiment of the subject matter of the invention, it can be provided that the support ribs are formed from punched and packaged sheets.

[0148] Finally, the invention can also be advantageously implemented such that at least one contact rib has a positive locking means on its surface directed radially inward toward a rotor shaft, via which a torque-transmitting connection can be established between the rotor shaft and the contact rib. The advantage resulting from this is, in particular, that a clear positioning of the rotor shaft and the contact rib relative to one another can be provided.

[0149] Outer ring

[0150] Particularly preferably, the rotor for an axial flux machine, in particular for an axial flux machine within a drive train of a motor vehicle, comprises a plurality of magnetic elements which are arranged circumferentially distributed in the rotor, wherein the magnetic elements are supported radially outwardly on an outer ring.

[0151] This support can be direct or indirect. With direct support, the magnetic element rests against the outer ring at least in part. With indirect support, there is at least a layer of material between the magnetic element and the outer ring.

[0152] This has the advantage that the usually quite brittle magnetic elements are better protected from mechanical influences and can evenly transfer the loads caused by centrifugal forces during rotor operation. The forces caused by the magnetic elements can thus be evenly transmitted over a wide circumferential area of ​​the outer ring to other components of the rotor, such as a bandage element. It is therefore preferred that the outer ring provides the magnetic elements with a "soft bedding" in order to effectively protect the brittle material of the magnetic elements from unwanted stress peaks. The outer ring can therefore preferably conform to the magnetic elements, which can be achieved in manufacturing terms, for example, through an injection molding process and / or via an interface layer such as an adhesive and / or via a material whose Young's modulus is lower than the material of the magnetic elements.This allows the force exerted by a magnetic element to be dissipated over the largest possible contact area, which can reduce local compressive stresses.

[0153] Furthermore, the outer ring can increase the axial rigidity of the rotor.

[0154] The outer ring can be injection-molded or cast, with filled or unfilled, reinforced or unreinforced polymer. It is also possible to form the outer ring from non-magnetic steel or ceramic.

[0155] According to an advantageous embodiment of the invention, it can be provided that an annular bandage element rests on the outer ring by means of a press fit, so that a preload is introduced into the rotor via the bandage element.

[0156] This allows a bandage element to be protected from direct contact with the typically quite rough magnetic elements. The outer ring thus separates the brittle, rough magnetic elements from the bandage element, which is generally comparatively notch-sensitive.

[0157] Furthermore, the outer ring can provide the bandage element with a uniform surface on its outer surface, which can simplify the pressing-on process of the bandage element and support a uniform load transfer into the bandage element. Furthermore, local (excessive) stresses on the bandage element in the transverse direction can be reduced or completely avoided. In addition, the outer ring can also provide a uniform outer surface over which a bandage element can be pressed on. This surface can also be

[0158] The pressing process can be brought to an exact size with which the overlap to the pressed-on bandage element can be adjusted.

[0159] The outer ring therefore locally absorbs and concentrates the forces arising from the magnetic elements and / or the stiffening struts during operation of the rotor and passes these forces on to the bandage element in a homogenized manner over a larger area.

[0160] According to a further preferred development of the invention, it can also be provided that the outer ring is circumferentially closed, which can be advantageous in particular from a manufacturing point of view but also with regard to the axial rigidity of the rotor.

[0161] Furthermore, according to a similarly advantageous embodiment of the invention, the outer ring can be formed from individual ring segments. In this case, in particular, a ring segment of the outer ring and a magnetic element can form a structural unit, which is then formed into a ring by circumferentially arranging a plurality of these structural units.

[0162] The outer ring can therefore be formed as a closed ring or from ring segments arranged to form a ring. The outer ring can be rolled from a stamped strip or cut from an extruded profile. It is also conceivable for an outer ring to be stamped and fanned out as a longitudinal structure from a plate.

[0163] According to a further particularly preferred embodiment of the invention, it can be provided that the outer ring comprises a plurality of pockets, each of which has a contact surface extending in the circumferential direction for a magnetic element and, on both sides of the magnetic element in the circumferential direction, a coupling section extending radially inward from the outer ring. This can, in particular, achieve the effect of improving the guidance and contact of the magnetic elements in the circumferential direction. Furthermore, the pockets also facilitate the manufacture of the rotor, since the magnetic elements can be positioned in a predefined position relative to the outer ring via the pockets, for example, prior to an injection molding or casting process.

[0164] Furthermore, the invention can also be further developed in such a way that between two magnetic elements adjacent in the circumferential direction, at least one stiffening strut is arranged which extends in the radial direction towards the outer ring, whereby load paths can also be transferred in a defined manner to the outer ring through the stiffening struts.

[0165] In a likewise preferred embodiment of the invention, it can also be provided that a plurality of stiffening struts are each supported radially on the outer ring, so that the stiffening struts can be prevented from tilting. Furthermore, this allows the forces of the stiffening struts to be transmitted particularly homogeneously to the bandage element. This contributes positively to the overall axial stiffness of the rotor disk.

[0166] It may also be advantageous to further develop the invention in such a way that at least one stiffening strut is supported in the radial direction on a coupling section of the outer ring, which can further improve the force transmission between the stiffening struts and the outer ring.

[0167] It would also be possible for a plurality of stiffening struts to be supported in the radial direction on a coupling section of the outer ring.

[0168] According to a further preferred embodiment of the subject matter of the invention, it can be provided that the outer ring is formed by means of an extrusion process, which is particularly advantageous in terms of production technology.

[0169] Finally, the invention can also be advantageously designed such that the outer ring has a polygonal outer contour with a plurality of support points. It has been shown that if the outer ring is polygonalized along its load introduction and support points, it exhibits advantageous rigidity and can absorb corresponding loads particularly well.

[0170] In this context, it is particularly preferred that the support points of the polygonal line be determined by the load-introducing elements. This anticipates the shape during loading in the unloaded structure, leading to increased initial stiffness.

[0171] The rotor for an axial flux machine, in particular for an axial flux machine within a drive train of a motor vehicle, preferably comprises an inner ring and an outer ring arranged coaxially thereto, and magnetic elements arranged between the inner ring and the outer ring, wherein stiffening struts extending in the radial direction are arranged in a spoke-like manner between the inner ring and the outer ring, and one of the magnetic elements is arranged on each side of a stiffening strut in the circumferential direction and is operatively connected to a stiffening strut in such a way that a force component caused by centrifugal force acting on the magnetic elements during operation of the rotor can be transferred from a magnetic element to a stiffening strut and / or vice versa.wherein at least one of the stiffening struts and / or at least one of the magnetic elements is connected to at least one cover plate which, on a first end face of the rotor, spans the rotor at least in sections, so that during operation of the rotor a force transmission can be effected from one of the stiffening struts and / or at least one of the magnetic elements to the at least one cover plate and / or vice versa.

[0172] This allows, on the one hand, the axial rigidity of the rotor to be increased. Furthermore, the rotor according to the invention allows the centrifugal loads of the magnetic elements to be distributed more evenly radially outward, for example, into the outer ring and / or into a bandage element. The inner ring can also be formed, for example, by a rotor shaft, so that the magnetic elements are supported radially inward on the rotor shaft, which functions as the inner ring.

[0173] Furthermore, the stiffening struts can have partial or complete direct contact with the bandage.

[0174] Furthermore, the cover plate allows for the provision of a homogeneous contact surface for contacting and absorbing the operating forces, for example, through a flange. The flange can advantageously be connected to the cover plate via a tightly toleranced contact surface, thereby enabling the occurring operating forces to be absorbed evenly and safely. For example, the cover plate can also distribute stress peaks caused by inhomogeneities in the rotor over larger areas, thus reducing them.

[0175] Furthermore, the cover plate can have beneficial effects on the acoustics and air friction during rotor operation thanks to its homogeneous, and particularly flat, surface. In the event of contact between the rotor and the stator, the cover plate can also minimize the effects of the contact and wear on the rotor's functional components. The cover plate can also serve as a type of wear element for the rotor to rub against the stator. This serves to protect the internal structure, and the cover plate can also be treated locally to minimize the effects of rub, for example, with a sliding layer for lower energy input, a local wear-resistant layer, and / or a sensor in the area of ​​a contact point to detect contact.

[0176] Preferably, stiffening struts extending in the radial direction between the inner ring and the outer ring are arranged in a spoke-like manner, with a magnetic element being arranged between each of the two stiffening struts adjacent in the circumferential direction.

[0177] According to an advantageous embodiment of the invention, it can be provided that in the circumferential direction on both sides of one of the stiffening struts a coupling element is arranged between one of the magnetic elements and the corresponding stiffening strut, wherein the coupling elements are formed from a material different from the inner ring and / or the outer ring and / or the magnetic elements and / or the stiffening struts.

[0178] According to a further preferred development of the invention, it can also be provided that at least one of the stiffening struts is constructed in multiple parts. It can also be provided that a majority of the stiffening struts are constructed in multiple parts. Furthermore, it is possible for all stiffening struts to be constructed in multiple parts.

[0179] Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that at least one of the stiffening struts is formed integrally with the inner ring and / or the outer ring. It can also be preferred that a majority of the stiffening struts are formed integrally with the inner ring and / or the outer ring. Most preferably, all stiffening struts are formed integrally with the inner ring and / or the outer ring.

[0180] The stiffening struts can be incorporated directly into the rotor using a primary forming process or subsequently installed. The stiffening struts can be machined, at least in some areas, before being installed in the rotor and again afterward.

[0181] According to a further particularly preferred embodiment of the invention, it can be provided that at least one material of at least one stiffening strut has an E-modulus of greater than 6000 MPa in the radial extension of the stiffening strut. It can also be preferred that at least one material of a plurality of stiffening struts has an E-modulus of greater than 6000 MPa in the radial extension of the stiffening struts. Furthermore, it is also preferred that at least one material of all stiffening struts has an E-modulus of greater than 6000 MPa in the radial extension of the stiffening strut. Furthermore, the invention can also be further developed such that at least one of the stiffening struts is formed from a plastic, in particular a fiber-reinforced plastic, non-magnetic steel, aluminum or a ceramic.

[0182] It is particularly preferred that the material of one of the stiffening struts is different from the material of the coupling elements and / or the inner ring and / or the outer ring and / or the magnetic elements

[0183] The stiffening struts can be produced by machining, pressing, winding, injection molding, potting, wet winding, or PrePreg with filled or unfilled, reinforced or unreinforced polymer. The reinforcements can be spherical, short fiber, long fiber, or continuous fiber, or a mixture thereof.

[0184] In a likewise preferred embodiment variant of the invention, it can also be provided that the stiffening struts, the magnetic elements and / or the inner ring have an opposite prestress to a load bandage and / or an auxiliary bandage at the operating point of the rotor.

[0185] It may also be advantageous to further develop the invention such that at least one of the stiffening struts is cuboid-shaped. Preferably, a majority of the stiffening struts are cuboid-shaped. Most preferably, all stiffening struts are cuboid-shaped.

[0186] According to a further preferred embodiment of the subject matter of the invention, it can be provided that a majority of the stiffening struts, preferably all stiffening struts, are designed essentially identically, which is advantageous in particular with regard to manufacturing costs.

[0187] Finally, the invention can also be advantageously implemented such that at least one of the stiffening struts is connected at one of its axial surfaces to a cover plate, which at least partially spans the rotor on one end face of the rotor. In this context, it can also be preferred for a plurality of the stiffening struts to be connected at one of their axial surfaces to a cover plate, which at least partially spans the rotor on one end face of the rotor. It is also highly preferred for all stiffening struts to be connected at one of their axial surfaces to a cover plate, which at least partially spans the rotor on one end face of the rotor.

[0188] The advantage that results from this is in particular that the stiffening struts enable a shear field transfer to the cover panels and / or vice versa.

[0189] The invention will be explained in more detail below with reference to figures without limiting the general inventive concept.

[0190] It shows:

[0191] Figure 1 is a perspective view of a rotor for an axial flow machine,

[0192] Figure 2 is an exploded view of a rotor for an axial flow machine,

[0193] Figure 3 is a cross-sectional view of a rotor of an axial flow machine,

[0194] Figure 4 is a cross-sectional detail view of the rotor shown in Figure 3,

[0195] Figure 5 isolated stiffening struts, outer ring and bandage element in a perspective view,

[0196] Figure 6 an outer ring in a cross-sectional view,

[0197] Figure 7 shows a detailed view of the contact surface of the outer ring in a cross-sectional view, Figure 8 shows a detailed view of a coupling element in the rotor in a cross-sectional view,

[0198] Figure 9 shows a rotor in three different manufacturing states, each in a cross-sectional view,

[0199] Figure 10 shows a first embodiment of a magnetic element in a cross-sectional view,

[0200] Figure 11 shows a first embodiment of a magnetic element in a perspective view,

[0201] Figure 12 shows a second embodiment of a magnetic element in a perspective view,

[0202] Figure 12 shows a third embodiment of a magnetic element in a perspective view,

[0203] Figure 14 shows a fourth embodiment of a magnetic element in a perspective view,

[0204] Figure 15 two embodiments of a bandage element in a perspective sectional view

[0205] Figure 16 a rotor in a perspective axial section view,

[0206] Figure 17 a rotor with cover discs in an axial section,

[0207] Figure 18 shows a free-standing inner ring with contact ribs and magnetic elements in a cross-sectional view,

[0208] Figure 19 shows a rotor without an inner ring in a cross-sectional view. Figure 20 shows two embodiments of an axial flow machine, each in a schematic axial sectional view.

[0209] Figure 21 a motor vehicle with an axial flow machine in a schematic representation

[0210] Figure 1 and Figure 2 show a rotor 1 for an axial flux machine 2, in particular for an axial flux machine 2 within a drive train 3 of a motor vehicle 4, as is also sketched in Figure 21.

[0211] The rotor 1 comprises an inner ring 5 and an outer ring 6 arranged coaxially thereto, wherein rod-like, rectangular-cross-section stiffening struts 7 are arranged in a spoke-like manner extending radially between the inner ring 5 and the outer ring 6. A magnetic element 8 is arranged between each of two circumferentially adjacent stiffening struts 7.

[0212] As can be clearly seen from Figure 3, a coupling element 9 is arranged in the circumferential direction on both sides of each of the stiffening struts 7 between one of the magnetic elements 8 and the corresponding stiffening strut 7. The coupling elements 9 are essentially identical.

[0213] The coupling elements 9 are formed from a material different from the inner ring 5 and / or the outer ring 6 and / or the magnetic elements 8 and / or the stiffening struts 7 and / or the contact ribs 60.

[0214] The magnetic elements 8 are held radially outward by a closed outer ring 6. The annular auxiliary bandage 12 with the annular load bandage 17 is connected to this. Radially inward, the magnetic elements 8 rest on the inner ring 5 via the contact ribs 60, which is coupled to the rotor shaft 23 via the flange 16. A cover plate 18, 19 is applied axially on each side. The flange 16 accommodates the inner ring 5 or the contact ribs 60 and is connected to the flange ring 20 with screws. The compression limiters 21 support the inner ring 5 and act as screw support elements.

[0215] The coupling element 9 serves to compensate for relative displacements between the magnetic elements 8 and other components and at the same time to reduce the normal tensile stress on the coupling elements 9. At the same time, the coupling elements 9 are used to transmit centrifugal forces of the magnetic elements 8 to the stiffening struts 7 and thus, among other things, to relieve the load on the cover layers. The coupling elements 9 bind the cover layers, i.e. the cover disks 18, 19, axially to the rotor 1 in order to keep the air gap between the rotor 1 and the stator 22 stable. Coupling elements 9, together with the pre-tensioned bandage (before the shaft is pressed in), also allow the rotor 1 to be subjected to circumferential pressure. For this purpose, an annular auxiliary bandage 12 rests against the outer ring 6. The elasticity of the coupling element 9 helps define the circumferential stiffness of the rotor 1 and can be specifically adjusted to the desired level.

[0216] Figures 3-4 show the rotor 1 with an inner ring 5, on which the stiffening struts are radially supported. However, if this rotor 1 is mounted on a rotor shaft 26 in a rotationally fixed manner, the inner ring 5 from Figures 3-4 can also be removed, for example by milling, before assembly on the rotor shaft 26, so that in the assembled state, the inner ring 5 is formed by the outer surface of the rotor shaft 26. This is shown in Figure 19, where the stiffening struts 7 are then radially supported directly on the rotor shaft 26.

[0217] The rotor 1 can be used in an axial flux machine 2 in H-configuration, as shown in figure a of Figure 20, or in I-configuration, which is shown in figure b of Figure 20.

[0218] Figure 4 shows a detailed view of the rotor 1 known from Figure 3. Here, too, the inner ring 5 and the outer ring 6 arranged coaxially thereto can be clearly seen, wherein stiffening struts 7 extending in the radial direction between the inner ring 5 and the outer ring 6 are arranged in a spoke-like manner, and a magnetic element 8 is arranged between each two stiffening struts 7 adjacent in the circumferential direction.

[0219] An annular bandage element 44 bears against the outer ring 6 by means of a press fit, so that a preload is introduced into the rotor 1 via the bandage element 44. The bandage element 44 can cover the outer ring 6 of the rotor 1 completely or partially in the axial direction. The bandage element 44 is designed in several parts, with at least one annular auxiliary bandage 12 bearing against the outer ring 6 and at least one annular load bandage 17 bearing against the auxiliary bandage 12. In principle, it would also be possible to design the bandage element 44 in one piece. Furthermore, it is also possible for only the auxiliary bandage 12 to be applied via a press fit, and the load bandage 17 to be positioned on it without any load. Of course, the auxiliary bandage 12 and the load bandage 17 can also be provided with a press fit.

[0220] The coupling elements 9 of the rotor 1 are explained in more detail below with reference to Figure 8. The coupling element 9 serves primarily to compensate for relative displacements between the magnetic elements 8 and other components, while simultaneously reducing the normal tensile stress on the coupling elements 9. At the same time, the coupling elements 9 are used to transmit centrifugal forces of the magnetic elements 8 to the stiffening struts 7, thus relieving, among other things, the cover layers. The coupling elements 9 axially connect the cover layers, i.e., the cover disks 18, 19, to the rotor 1 in order to keep the air gap between the rotor 1 and the stator 22 stable.

[0221] Coupling elements 9, together with the pre-tensioned bandage (before the shaft is pressed in), also allow the rotor 1 to be subjected to circumferential pressure. For this purpose, an annular auxiliary bandage 12 rests against the outer ring 6. The elasticity of the coupling element 9 helps define the circumferential stiffness of the rotor 1 or adjusts it to the desired level.

[0222] The coupling elements 9 are preferably formed from a material that has a modulus of elasticity between 400 MPa and 46,000 MPa and exhibits elastic behavior during operation of the rotor 1. As shown in Figure 8, the coupling elements 9 are rod-shaped and have an average thickness 10 in the circumferential direction of at least 0.47 mm, preferably 0.5-10 mm, particularly preferably 0.5-5 mm. Furthermore, in the region of the magnetic elements 8, the coupling elements 9 have a connecting section 13 that deviates from a rod shape and partially abuts one of the magnetic elements 8. The stiffening struts 7 are cuboid-shaped, with the coupling elements 9 each abutting at least partially against a longitudinal surface 11 of one of the stiffening struts 7.

[0223] A possible manufacturing process for the rotor 1 is shown in Figure 9: The rotor 1 is manufactured by equipping a tool with at least the magnetic elements 8, which can be expanded with, among other things, the compression limiter 21 and stiffening struts 7. Subsequently, in one or more steps, the outer ring 6 and the contact ribs 60, including the possibly only temporarily present inner ring 5, are injection-molded, attached or connected. After that, the cover disks 18, 19 can be applied and any remaining filling areas can be filled with a filling compound. The rotor 1 can be circumferentially preloaded using an auxiliary bandage 12 before the rotor shaft 23 is pressed in. A load bandage 17 radially outside the auxiliary bandage 12 can also be applied with preload, if desired. Subsequently, the central bore and shaft holder are produced by removing most or all of the inner ring 5.Pressing on the rotor shaft 23 with axial fixation of the flange 16 represents the interface to the rotor 1. The rotor 1 is balanced in a balancing process on the flange 16, the flange slide 20, the outer ring 6 or on the coupling elements 9.

[0224] A first method for producing a rotor 1 for an axial flux machine 2 can, as explained again, comprise the following steps: First, a molding tool 14, a plurality of stiffening struts 7, and a plurality of magnetic elements 8 are provided.

[0225] The stiffening struts 7 and the magnetic elements 8 are then arranged in the molding tool 14 such that the stiffening struts 7 are positioned spoke-like and a magnetic element 8 is arranged between each two circumferentially adjacent stiffening struts 7, and an air space 15 is provided on each side of each of the stiffening struts 7 between one of the magnetic elements 8 and the corresponding stiffening strut 7 in the molding tool 14. This manufacturing state can be seen in illustration a of Figure 9.

[0226] Subsequently, injection molding is carried out to form an inner ring 5 and an outer ring 6 using the mold 14, so that the position of the stiffening struts 7, the magnetic elements 8, the inner ring 5 and the outer ring 6 relative to one another is fixed, which is shown in Figure b of Figure 9.

[0227] The air spaces 15 on both sides of one of the stiffening struts 7 are now filled with a material that is different from the material of the inner ring 5 and / or the outer ring 6 and / or the magnetic elements 8 and / or the stiffening struts 7, so that a coupling element 9 is formed between each of the magnetic elements 8 and the corresponding stiffening strut 7. Filling can be performed by means of an injection molding process in the mold 14 or a casting process. However, filling can also take place only after one or both cover disks 18, 19 have been applied.

[0228] Alternatively, it would also be possible to first provide a molding tool 14, a plurality of stiffening struts 7, a plurality of magnetic elements 8, and a plurality of coupling elements 9 with a material that is different from the material of an inner ring 5 and / or an outer ring 6 and / or the magnetic elements 8 and / or the stiffening struts 7.

[0229] Thus, first, an arrangement of the stiffening struts 7 and the magnetic elements 8 is carried out in the molding tool, so that the stiffening struts 7 are positioned like spokes and a magnetic element 8 is arranged between each two stiffening struts 7 adjacent in the circumferential direction, and wherein on both sides of one of the stiffening struts 7 an air space 15 is provided between one of the magnetic elements 8 and the corresponding stiffening strut 7 in the molding tool 14.

[0230] The inner ring 5 and the outer ring 6 are then injection-molded using the mold 14, so that the relative positions of the stiffening struts 7, the magnetic elements 8, the inner ring 5, and the outer ring 6 are determined. Finally, the coupling elements 9 are inserted into the air spaces 15 on either side of one of the stiffening struts 7.

[0231] Figure c of Figure 9 then shows the rotor 1 with the coupling elements 9 inserted.

[0232] The rotor 1 can be used in an axial flux machine 2 in H-configuration, as shown in figure a of Figure 9, or in I-configuration, which is shown in figure b of Figure 9.

[0233] Figure 10 shows a magnetic element 8 for a rotor 1 of an axial flux machine 2, wherein the magnetic element 8 has a longitudinal extension 24 and a circumferential contour 25.

[0234] On a first side 26, which, when the magnetic element 8 is installed in the rotor 1, faces a first direction of rotation of the rotor 1, a longitudinally extending first planar surface section 27 and a longitudinally extending second planar surface section 28 are formed. When the magnetic element 8 is installed in the rotor 1, the first surface section 27 is positioned radially above the second surface section 28.

[0235] In the embodiment shown in Figure 10, the magnetic element 8 is formed mirror-symmetrically with respect to its longitudinal extent 24. Thus, on a second side 29, which faces a second direction of rotation of the rotor 1 when the magnetic element 8 is installed in the rotor 1, a third flat surface section 30 extending in the longitudinal direction and a fourth flat surface section 31 extending in the longitudinal direction are formed, wherein when the magnetic element 8 is installed in the rotor 1, the third surface section 30 is positioned radially above the fourth surface section 31.

[0236] The surface sections 27, 28, 30, 31 are arranged and shaped such that a first plane 32 running through the first surface section 27 and a third plane 33 running through the third surface section 30 intersect radially above the magnetic element 8 in the direction of the longitudinal extent 24 when the magnetic element 8 is installed in the rotor 1, and a second plane 34 running through the second surface section 28 and a fourth plane 35 running through the fourth surface section 31 intersect radially below the magnetic element 8 in the direction of the longitudinal extent 24 when the magnetic element 8 is installed in the rotor 1.

[0237] The first flat surface section 27 and the third flat surface section 30 have a length in the circumferential direction of the magnetic element 8 of at least 2 mm and a maximum of 48 mm. The first flat surface section 27 and the third flat surface section 30 can serve for sealing, radial positioning in the tool during the manufacture of the rotor 1, and as a reference surface for magnet sorting (center of mass relative to geometric shape).

[0238] Figure 10 further shows that the circumferential contour 25 has a fifth surface section 39 which, when installed in the rotor 1, is oriented radially outwards and connects the first surface section 27 to the third surface section 30, wherein the fifth surface section 39 has a circular arc-shaped contour whose axis of rotation runs coaxially to a rotational axis of the rotor 1. The magnetic element 8 therefore has a contour on its radially outer surface which essentially follows a circular arc whose center is concentric to the rotational axis of the rotor 1. As a result of this contour, the (centrifugal) loads generated by the magnetic element 8 are transmitted evenly to the radially outer component regions (e.g. the auxiliary band 12 or the load band 17). In addition, the magnetic element 8 thereby supports these outer regions evenly.What can also be seen from Figure 10 is that the magnetic element 8 has an upper region 42 and a lower region 43, wherein the upper region 42 extends above half of the longitudinal extension 24 of the magnetic element 8 and the lower region 43 extends below half of the longitudinal extension 24 of the magnetic element 8. The first surface section 27 and the third surface section 30 extend exclusively within the upper region 42 of the magnetic element 8.

[0239] From the embodiment shown in Figure 11, it can be seen that the circumferential contour 25 can have a chamfer 36 formed at the transition between the circumferential contour 25 and an axial surface 37. In this example, the chamfer 36 runs circumferentially around the circumferential contour 25. The chamfer 36 can contribute to improving the adhesion of a magnetic element 8 to the adjacent components in the region of the circumferential contour 25, for example, to enable a thicker and thus more elastic adhesive layer or connecting layer towards the magnetic element 8. The chamfer 36 can vary in terms of its contour over its course along the circumference of the magnet.

[0240] Figure 12 shows an embodiment of a magnetic element 8 in which the circumferential contour 25 has a sixth surface section 40 which, when installed in the rotor 1, is oriented radially inward and connects the second surface section 28 to the fourth surface section 31, wherein the sixth surface section 40 has a chamfer 41 formed at the transition between the sixth surface section 28 and an axial surface 37. This defines a wedge-like contour on the sixth surface section 40, which can simplify the connection of the magnetic element 8 to, for example, an inner ring 5 of the rotor 1.

[0241] As shown in Figures 13-14, the second flat surface section 28 and the fourth flat surface section 31 can each have structures 38 that protrude or protrude at least partially from the respective flat surface. These structures 38 are designed as a profile, which provides a type of undercut in the radial direction for a positive fit in the adhesive connection or connection. At the very least, this profile should be designed in such a way that it results in an increase in the surface area for the connection and optimizes the support of operating loads.

[0242] As can be seen, for example, in Figure 4, an annular bandage element 44 can bear against the outer ring 6 of the rotor 1 by means of a press fit, so that a preload is introduced into the rotor 1 via the bandage element 44. In this embodiment shown, the bandage element 44 is designed in several parts, with at least one annular auxiliary bandage 12 bearing against the outer ring 6 and at least one annular load bandage 17 bearing against the auxiliary bandage 12, wherein the material of the auxiliary bandage 12 is different from the material of the load bandage 17.

[0243] At least one material of the multi-part bandage element 44, in particular the load bandage 17, has a modulus of elasticity >48,000 MPa in the circumferential direction of the bandage element 44. In this case, the preload introduced into the rotor 1 by the auxiliary bandage 12 is greater than the preload introduced by the load bandage 17. The bandage element 44 can even be configured such that the load bandage 17 rests against the auxiliary bandage 12 in such a way that it does not introduce any preload into the rotor 1.

[0244] The outer ring 6 has a polygonal outer contour 45 with a plurality of support points 46.

[0245] The bandage element 44 can be attached to the rotor 1, for example, as follows: First, a rotor 1 is provided with an inner ring 5 and an outer ring 6 arranged coaxially thereto, wherein stiffening struts 7 extending in the radial direction between the inner ring 5 and the outer ring 6 are arranged like spokes, and a magnetic element 8 is arranged between each two stiffening struts 7 adjacent in the circumferential direction. Then, an annular bandage element 44 is arranged on the outer ring 6 by means of a press fit, so that a preload is introduced into the rotor 1 via the bandage element 44. Finally, the rotor 1 is coupled to a rotor shaft 23. The stiffening struts 7 are explained in more detail below with reference to Figures 4 and 5._Figure 4 shows the rotor 1 comprising an inner ring 5 and an outer ring 6 arranged coaxially thereto, and magnetic elements 8 arranged between the inner ring 5 and the outer ring 6, wherein stiffening struts 7 are arranged in a spoke-like manner in radial R between the inner ring 5 and the outer ring 6.

[0246] In the circumferential direction on both sides of a stiffening strut 7, one of the magnetic elements 8 is arranged and operatively connected to a stiffening strut 7 in such a way that a force component caused by centrifugal force acting on the magnetic elements 8 during operation of the rotor 1 can be transferred from a magnetic element 8 to a stiffening strut 7 and / or vice versa.

[0247] Figure 4 further shows that, in the circumferential direction, on both sides of each of the stiffening struts 7, a coupling element 9 is arranged between one of the magnetic elements 8 and the corresponding stiffening strut 7, wherein the coupling elements 9 are formed from a material different from the inner ring 5 and / or the outer ring 6 and / or the magnetic elements 8 and / or the stiffening struts 7. The material of a stiffening strut 7 has a modulus of elasticity of greater than 6000 MPa in the radial extension of the stiffening strut 7.

[0248] The stiffening struts 7 are cuboid-shaped and essentially identical. The stiffening struts 7 are connected at least on one of their axial surfaces 50 to a cover plate 18, 19, which spans at least some sections of the rotor 1 on an end face 51, which can also be clearly seen in Figure 16.

[0249] By inserting the radial stiffening struts 7 parallel (relative to the load direction) to the magnetic element load path, the magnetic load path can be closed via the bandage element 44, the rotor shaft 23 or the inner ring 5, and the contact ribs 60. By applying opposing preload to the components involved at the operating point of the rotor 1, the stiffening struts 7 contribute directly to the overall stiffness of the rotor 1. This reduces the radial stress amplitudes in the magnetic elements and, if applicable, in their coupling elements 9. In addition, the overall radial stiffness of the rotor 1 increases (relative to the magnet displacement per centrifugal load), which reduces the displacement amplitudes and thus the relative stresses between the components.

[0250] The stiffening struts 7 thus transmit the magnetic centrifugal loads at additional points via the outer ring 6 into the bandage element 444, thus generating a more homogeneous and less polygonal load introduction into the load bandage. The magnetic forces are transferred to the stiffening struts 7 via the load paths "magnetic element-cover plate-stiffening strut" and "magnetic element-coupling element-stiffening strut." The stiffening struts 7 then transfer the loads to the bandage element 44.

[0251] The stiffening struts 7 are preloaded against the bandage element 44 via a press fit to the rotor shaft 23. This not only introduces a preload force into the bandage element 44, but also polygonizes it to absorb the operating forces more effectively (higher operating point stiffness than an originally round bandage element 44).

[0252] The stiffening struts 7 are located between the two cover plates 18, 19, which is clearly visible in Figure 16. They serve as shear field transmitters for the cover plates 18, 19, thereby increasing their effect on the axial stiffness. This effect can be further enhanced by partially aligning the direction of some of the reinforcing fibers in the stiffening struts 7 with the main load direction of the shear field. Of course, the stiffening struts 7 also directly contribute to increasing the axial rotor stiffness through their own area moment of inertia.

[0253] The outer ring 6, for example, can be clearly seen in Figures 6-7 and is described in more detail below. Figure 7 shows the rotor 1, comprising a plurality of magnetic elements 8 arranged circumferentially distributed within the rotor 1, wherein the magnetic elements 8 are supported radially outwardly on an outer ring 6.

[0254] An annular bandage element 44 rests against the outer ring 6 by means of a press fit, so that a preload is introduced into the rotor 1 via the bandage element 44.

[0255] Figure 6 clearly shows that the outer ring 6 is circumferentially closed. In principle, it would also be conceivable for the outer ring to be segmented. Figure 6 further shows that the outer ring 6 comprises a plurality of pockets 70, each of which has a circumferentially extending contact surface 71 for a magnetic element 8 and, on both sides of the magnetic element 8 in the circumferential direction, a coupling section 72 extending radially inward from the outer ring 6.

[0256] Between two circumferentially adjacent magnetic elements 8, a stiffening strut 7 is arranged, extending radially toward the outer ring 6. These stiffening struts 7 are each supported radially on a coupling section 72 of the outer ring 6.

[0257] The outer ring 6 has a polygonal outer contour 45 with a plurality of support points 46.

[0258] The cover discs 18, 19 are explained in more detail with reference to Figures 16-17. Figure 16 shows a rotor 1 comprising an inner ring 5 and an outer ring 6 arranged coaxially therewith, and magnetic elements 8 arranged between the inner ring 5 and the outer ring 6, wherein stiffening struts 7 extending in the radial direction are arranged in a spoke-like manner between the inner ring 5 and the outer ring 6.

[0259] In the circumferential direction, one of the magnetic elements 8 is arranged on each side of a stiffening strut 7 and is operatively connected to a stiffening strut 7 in such a way that a force component caused by centrifugal force acting on the magnetic elements 8 during operation of the rotor 1 can be transferred from a magnetic element 8 to a stiffening strut 7 and / or vice versa.

[0260] At least one of the stiffening struts 7 and / or at least one of the magnetic elements 8 is connected to at least one cover plate 18, which spans the rotor 1 at least in sections on a first end face 51 of the rotor 1, so that during operation of the rotor 1, a force transmission can be effected from one of the stiffening struts 7 and / or at least one of the magnetic elements 8 to the at least one cover plate 18 and / or vice versa.

[0261] Furthermore, at least one of the stiffening struts 7 and / or at least one of the magnetic elements 8 is connected to at least one cover plate 19, which spans the rotor 1 at least in sections on a second end face 52 of the rotor 1, so that during operation of the rotor 1, a force transmission can be effected from one of the stiffening struts 7 and / or at least one of the magnetic elements 8 to the at least one cover plate 19 and / or vice versa.

[0262] The cover disk 18 on the first end face 51 of the rotor 1 and the cover disk 19 on the second end face 52 of the rotor 1 are each formed in the shape of an annular disk. The cover disk 18 on the first end face 51 of the rotor 1 and the cover disk 19 on the second end face 52 of the rotor 1 each have a mean axial extent 58 that corresponds to between 1% and 80% of the axial extent 59 of the magnetic elements 8.

[0263] The cover plate 18 on the first end face 51 of the rotor 1 and the cover plate 19 on the second end face 52 of the rotor 1 have fastening means 55, by means of which a torque can be transmitted from the rotor 1 to a rotor flange 16, via which the torque can be introduced into a rotor shaft 23. In the embodiment shown, the fastening means 55 comprise equidistantly arranged on a circular path

[0264] Fastening openings 56. In the illustrated embodiment of the rotor 1, the cover plate 18 on the first end face 51 of the rotor 1 and the cover plate 19 on the second end face 52 of the rotor 1 are essentially identical. By attaching at least one cover plate 18, 19, the axial rigidity of the rotor 1 is increased, since the cover plate 18, 19 has rigidity in its plane. Through its connection to the rotor 1 and the load transfer via stiffening struts 7 and / or magnetic elements 8 and / or other rotor components, a shear field is transmitted at least into the rotor structure, preferably to the other cover plate 18, 19. This results in an increase in the area moment of inertia and thus the axial rigidity of the rotor 1.The cover discs 18, 19 also effect a centrifugal load transfer from the magnetic elements 8 via cover discs 18, 19 to the stiffening struts 7 for uniform load introduction of the centrifugal loads into the outer ring 6 or the bandage element 44.

[0265] The cover plates 18, 19 also even out the forces acting on the rotor 1 in the area of ​​the flange connection. This allows the operating forces of the rotor 1 to be transmitted homogeneously to the flange 16 via the contact surface. Likewise, the pressing forces of the flange connection can be evenly distributed into the rotor 1. Any auxiliary elements, such as knurls in the flange 16, can also engage a cover plate 18, 19.

[0266] Figure 16 further shows that the cover plate 18 on the first end face 51 of the rotor 1 and / or the cover plate 19 on the second end face 52 of the rotor 1 can have indentations 57 directed towards the inside or outside of the rotor 1, which result in a lower overall rigidity with respect to the radial rotor plane and can therefore locally relieve the cover plates 18, 19 or the rotor 1.

[0267] A radially inner region of a cover plate 18, 19, which is in contact with the flange 16, can be used as a machining layer to achieve a defined surface with desired properties to improve the connection to the flange 16. Figure 17 shows a variant in which the cover plate 18 on the first end face 51 of the rotor 1 and the cover plate 19 on the second end face 52 of the rotor 1 protrude radially beyond the edge of the outer ring 6, and a bandage element 44 rests axially on the outer ring 6 between the cover plates 18, 19. The cover plates 18, 19 can thus be used, for example, as a direct winding form or as an auxiliary form for the production of the load bandage 17. They can also act to protect the bandage element.

[0268] The inner ring 5 of the rotor 1 is explained in more detail with reference to Figure 4 and Figure 18. Figure 18 shows the rotor 1 comprising a plurality of magnetic elements 8, which are arranged circumferentially distributed in the rotor 1, wherein the magnetic elements 8 are supported radially inwardly on an inner ring 5 via the contact ribs 60.

[0269] The rotor 1 further has an outer ring 6 arranged coaxially with the inner ring 5, on which the magnetic elements 8 are supported radially outward, as can be seen in Figure 4. Between two circumferentially adjacent support ribs 60, a stiffening strut 7 is arranged, extending radially between the inner ring 5 and the outer ring 6.

[0270] A plurality of contact ribs 60 extend radially outward from the inner ring 5, with the magnetic elements 8 being supported radially inward against the contact ribs 60. The number of contact ribs 60 corresponds to the number of magnetic elements 8. The inner ring 5 and the contact ribs 60 are formed integrally, in particular monolithically. The inner ring 5 and the contact ribs 60 are formed by means of an extrusion process.

[0271] The inner ring 5 thus also connects the inner components of the rotor 1, making them particularly easy to handle during the manufacturing process. The inner ring 5 thus provides a defined inner contour, a cylindrical inner contour in the illustrated embodiment, to enable the rotor 1 to be specifically accommodated in a handling tool during the manufacturing process.

[0272] Each of the support ribs 60 has an opening 61 which axially passes through the respective support rib 60 and is penetrated by a screw by means of which the rotor flange 16 can be connected to the rotor 1.

[0273] As can also be clearly seen from Figure 18, the inner ring 5 with its contact ribs 60 and the magnetic elements 8 supported thereon are each arranged in alignment and mirror-symmetrically along a radially extending axis of symmetry 65.

[0274] The inner ring 5 can also be removed from the rotor 1, as can be seen in the embodiment of Figure 19. For example, the inner ring 5 can be completely machined for this purpose.

[0275] The support ribs 60 will now be described in more detail with reference to Figure 4, Figure 18 and Figure 19.

[0276] Figure 4 shows the rotor 1 comprising a plurality of magnetic elements 8, which are arranged circumferentially distributed within the rotor 1, wherein the magnetic elements 8 are supported radially inwardly on a plurality of contact ribs 60. The contact ribs 60 thus directly or indirectly create a positive connection with the corresponding magnetic elements in order to absorb and transmit their torque.

[0277] Furthermore, the contact ribs 60 make it possible to design a defined axial rigidity of the rotor 1 in order, for example, to be able to establish a force-locking (axial) frictional connection to a cover disk 18, 19 in order to support the cover disk 18, 19 axially and to be able to transmit the torque.

[0278] In the embodiment shown, the number of magnetic elements 8 corresponds to the number of contact ribs 60. The contact ribs 60 each have an opening 61 extending axially through the respective contact rib 60, through which the torque is transmitted to a cover plate 18, 19 and / or a rotor flange 16 and / or to enable a screw connection. For this purpose, the opening can have an internal thread or be designed as a through hole.

[0279] Between each of the two circumferentially adjacent support ribs 60, a radially extending stiffening strut 7 is arranged, which extends radially outward from an inner ring 5. The support ribs 60 are essentially identical.

[0280] The contact ribs 60 between the shaft connection and the magnetic elements 8 can also enable the rotor shaft 23 to be pressed in to achieve an interference fit and frictional engagement with the magnetic elements 8 and the rotor shaft 23. This, in turn, enables torque transmission to the rotor shaft 23.

[0281] Additionally or alternatively, positive locking details can be provided at the contact point between the contact rib and the shaft press fit to enable torque transmission and the torsion-proof seating of the contact ribs 60 on the rotor shaft 23. Thus, at least one contact rib 60 can have a positive locking means 63 on its surface 62 directed radially inward toward a rotor shaft 23, via which a torque-transmitting connection can be established between the rotor shaft 23 and the contact rib 60. In this case, the rotor 1 then has no inner ring 5, since the contact ribs 60 are directly coupled to the rotor shaft 23. This is illustrated in Figure 19.

[0282] The contact ribs 60 thus also serve to transmit the contact rib / rotor shaft overlap by pressing in the rotor shaft, in order to bring the load path rotor shaft-contact rib-magnetic element-outer ring-bandage element into a favorable compressive preload. The contact ribs 60 also serve as radial stiffness elements in the bracing diagram with, among others, bandage element 44 and stiffening struts 7, to distribute the total load amplitude across various preloaded spring paths and thus reduce the stress amplitude in the components involved. For this purpose, the radial stiffness of the contact ribs 60 must be less than 92% of the radial stiffness of the magnetic elements 8.

[0283] In all embodiments shown, the rotor 1 preferably contains no ferromagnetic material. The components of the rotor 1, with the exception of the magnetic elements 8, are therefore preferably made of a non-ferromagnetic material, such as plastic, ceramic, non-magnetic steel, or aluminum. Most preferably, all components from the group comprising the inner ring 5, the outer ring 6, the stiffening struts 7, the coupling elements 9, the auxiliary bandage 12, the load bandage 17, the cover plates 18, 19, and the support ribs 60 are made of a plastic.

[0284] 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.

[0285] List of reference symbols

[0286] 1 rotor

[0287] 2 axial flux machine

[0288] 3 Drivetrain

[0289] 4 Motor vehicle

[0290] 5 inner ring

[0291] 6 Outer ring

[0292] 7 stiffening struts

[0293] 8 magnetic elements

[0294] 9 Coupling element

[0295] 10 strength

[0296] 11 Longitudinal surface

[0297] 12 Auxiliary bandage

[0298] 13 connecting section

[0299] 14 mold tool

[0300] 15 Airspace

[0301] 16 flange

[0302] 17 Load bandage

[0303] 18 Cover plate

[0304] 19 Cover plate

[0305] 20 flange ring

[0306] 21 Compression Limiter

[0307] 22 Stator

[0308] 23 Rotor shaft

[0309] 24 Longitudinal extension

[0310] 25 Circumferential contour

[0311] 26 page

[0312] 27 Area section

[0313] 28 Area section

[0314] 29 Page

[0315] 30 area section

[0316] 31 area section

[0317] 32 Level 33 Level

[0318] 34 Level

[0319] 35 Level

[0320] 36 chamfer

[0321] 37 Axial surface

[0322] 38 structures

[0323] 39 Area section

[0324] 40 area section

[0325] 41 chamfer

[0326] 42 Area

[0327] 43 Area

[0328] 44 Bandage element

[0329] 45 Contour

[0330] 46 support points

[0331] 50 axial surfaces

[0332] 51 front side

[0333] 52 front side

[0334] 55 fasteners

[0335] 56 fasteners

[0336] 57 vaults

[0337] 58 Extension

[0338] 59 Extension

[0339] 60 attachment ribs

[0340] 61 Opening

[0341] 62 area

[0342] 63 Form-locking devices

[0343] 65 axis of symmetry

[0344] 70 bags

[0345] 71 contact surface

[0346] 72 Coupling section

Claims

Claims 1. Rotor (1) for an axial flow machine (2), in particular for an axial flow machine (2) within a drive train (3) of a motor vehicle (4), comprising an inner ring (5) and an outer ring (6) arranged coaxially thereto, wherein in the radial direction between the inner ring (5) and the outer ring (6) extending stiffening struts (7) are arranged spoke-like, and between two circumferentially adjacent stiffening struts (7) in each case a magnetic element (8) is arranged, characterized in that in the circumferential direction on both sides of one of the stiffening struts (7) in each case a coupling element (9) is arranged between one of the magnetic elements (8) and the corresponding stiffening strut (7), wherein the coupling elements (9) are formed from a material different from the inner ring (6) and / or the outer ring (6) and / or the magnetic elements (8) and / or the stiffening struts (7).

2. Rotor (1) according to claim 1, characterized in that the coupling elements (9) are formed from a material having an E-modulus between 400MPa and 46,000MPa.

3. Rotor (1) according to claim 1 or 2, characterized in that the coupling elements (9) are formed from a material which has an elastic behavior during operation of the rotor (1).

4. Rotor (1) according to one of the preceding claims, characterized in that the coupling elements (9) are rod-shaped and have an average thickness (10) of >0.47 mm, preferably 0.5-10 mm, particularly preferably 0.5-5 mm in the circumferential direction.

5. Rotor (1) according to one of the preceding claims, characterized in that the coupling elements (9) have at least one connecting section (13) which deviates from a rod shape and which at least partially rests against one of the magnetic elements (8).

6. Rotor (1) according to one of the preceding claims, characterized in that the coupling elements (9) are substantially identical.

7. Rotor (1) according to one of the preceding claims, characterized in that the stiffening struts (7) are cuboid-shaped, wherein the coupling elements (9) each bear at least in sections against a longitudinal surface (11) of one of the stiffening struts (7).

8. Rotor (1) according to one of the preceding claims, characterized in that an annular auxiliary bandage (12) rests on the outer ring (6).

9. Method for producing a rotor for an axial flow machine (2), in particular for an axial flow machine (2) within a drive train (3) of a motor vehicle (4), comprising the following steps: Providing a molding tool (14), Providing a plurality of stiffening struts (7), Providing a plurality of magnetic elements (8), - Arrangement of the stiffening struts (7) and the magnetic elements (8) in the molding tool, so that the stiffening struts (7) are positioned like spokes and a magnetic element (8) is arranged between each of two circumferentially adjacent stiffening struts (7), and wherein on both sides of one of the stiffening struts (7) an air space (15) is provided between one of the magnetic elements (8) and the corresponding stiffening strut (7) in the molding tool (14), - injection moulding of an inner ring (5) and an outer ring (6) using the mould (14) so that the position of the stiffening struts (7), the magnetic elements (8), the inner ring (5) and the outer ring (6) relative to one another is fixed, - filling the air spaces (15) on both sides of one of the stiffening struts (7) with a material which is different from the material of the inner ring (6) and / or the outer ring (6) and / or the magnetic elements (8) and / or the stiffening struts (7), so that a coupling element (9) is formed between one of the magnetic elements (8) and the corresponding stiffening strut (7).

10. Method for producing a rotor for an axial flow machine (2), in particular for an axial flow machine (2) within a drive train (3) of a motor vehicle (4), comprising the following steps: - provision of a molding tool (14), - providing a plurality of stiffening struts (7), - providing a plurality of magnetic elements (8), - Providing a plurality of coupling elements (9) with a material that is different from the material of an inner ring (6) and / or an outer ring (6) and / or the magnetic elements (8) and / or the stiffening struts (7), - Arrangement of the stiffening struts (7) and the magnetic elements (8) in the molding tool, so that the stiffening struts (7) are positioned like spokes and a magnetic element (8) is arranged between each of two stiffening struts (7) adjacent in the circumferential direction, and wherein on both sides of one of the stiffening struts (7) a Air space (15) is provided between one of the magnetic elements (8) and the corresponding stiffening strut (7) in the molding tool (14), - injection molding of the inner ring (5) and the outer ring (6) using the molding tool (14) so that the position of the stiffening struts (7), the magnetic elements (8), the inner ring (5) and the outer ring (6) relative to one another is fixed, - inserting the coupling elements (9) into the air spaces (15) on both sides of one of the stiffening struts (7)

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