Electric axial flux machine

Abstract

The invention relates to an electric axial flux machine (1) comprising a stator (2) with a first partial stator (21) and with a second partial stator (22) arranged axially spaced from the first partial stator (21), and a rotor (3) with a disk-shaped rotor body (31) arranged on a rotor shaft (30) and axially positioned between the first partial stator (21) and the second partial stator (22), wherein the first partial stator (21) and the second partial stator (22) are movably arranged in the axial direction relative to the rotor body (31). Furthermore, an adjusting device (4) is provided, wherein the adjusting device (4) is configured to adjust the first partial stator (21) and the second partial stator (22) in the axial direction to set an air gap (L1, L2).According to the invention, the adjusting device (4) is configured to adjust the first partial stator (21) and the second partial stator (22) in the axial direction depending on a torque to be transmitted via the rotor shaft (3), which generates a supporting torque resulting on the first partial stator (21) and on the second partial stator (22).

Description

The present invention relates to an electric axial flux machine in an I-arrangement, comprising a stator with a first sub-stator and a second sub-stator arranged axially spaced from the first sub-stator, and a rotor with a disk-shaped rotor body arranged on a rotor shaft and axially positioned between the first sub-stator and the second sub-stator, wherein the first sub-stator and the second sub-stator are movably arranged in the axial direction relative to the rotor body. The axial flux machine further comprises an adjustment device, wherein the adjustment device is configured to adjust the first sub-stator and the second sub-stator in the axial direction to set an air gap. Electric axial flux machines are already well known from the prior art. Axial flux machines are already well known in the prior art. From EP 2 985 893 A1, an electric axial flux machine with a stator and a rotor is known, wherein the stator comprises at least two stator segments, and wherein the rotor is connected to a rotor shaft, wherein the rotor and / or the rotor shaft are rotatably mounted in a bearing, and wherein the stator segments are arranged so as to be fixed relative to the bearing in the direction of rotation of the rotor. At least one of the stator segments is arranged so as to be movable in the axial or radial direction relative to the bearing in order to adjust the width of the air gap between the rotor and the stator segments. Furthermore, DE 10 2019 131 198 A1 describes a modular axial flux motor for automated guided vehicles (AGVs), comprising at least one disc-shaped stator and at least one disc-shaped rotor rotatable relative to the stator. The rotor and stator are arranged axially side by side. The stator includes electrical coils. The rotor has at least one permanent magnet with alternating poles. The rotor shaft is conventionally mounted in housing side walls or the like via rolling bearings. In most cases, the rolling bearings are preloaded axially by means of springs so that the rolling element balls are subjected to force and guided in contact with the raceways between the inner ring and the outer ring. DE 10 2020 114 855 B3 further discloses an electric machine, designed as a permanent magnet synchronous machine, comprising a rotor with at least one rotor body arranged on a rotor shaft and a stator, as well as an adjustment device configured to generate the axial relative movement between the at least one rotor body and the stator as a function of a torque occurring between the rotor shaft and the at least one rotor body in the direction towards the stator. The at least one adjustment device comprises a first adjustment element, a second adjustment element, and at least one rolling element arranged between the first adjustment element and the second adjustment element. The first adjustment element is arranged axially displaceable and with limited rotational freedom on the rotor shaft, which is axially fixed, and the second adjustment element is connected to the rotor shaft in a rotationally and displacement-resistant manner.The adjusting elements are designed in such a way that, in the event of a rotation of the first adjusting element against the second adjusting element or vice versa, at least one rotor body is axially displaced on the rotor shaft against the spring force. An electric axial flux machine according to the preamble of claim 1 is described in US 2009 / 0 134 723 A1. Regarding further state of the art, reference is made to DE 10 2020 104 857 A1, DE 10 2020 113 905 A1 and US 5 982 070 A. The object of the present invention is to provide an axial flux machine in an I-arrangement which is improved with regard to torque-dependent field amplification. This problem is solved by an electric axial flux machine with the features of claim 1. An axial flux machine according to the invention comprises a stator with a first partial stator and with a second partial stator arranged axially spaced from the first partial stator, and a rotor with a disk-shaped rotor body arranged on a rotor shaft and axially positioned between the first partial stator and the second partial stator, wherein the first partial stator and the second partial stator are movably arranged in the axial direction relative to the rotor body. Furthermore, the axial flux machine according to the invention comprises an adjustment device, wherein the adjustment device is configured to adjust the first partial stator and the second partial stator in the axial direction to set an air gap.According to the invention, the adjusting device is configured to adjust the first and second stator sections in the axial direction as a function of a torque transmitted via the rotor shaft, which generates a supporting torque acting on the first and second stator sections. This achieves the advantage of enabling an operating-situation-dependent adjustment of the air gap between the stator and rotor without the need for additional actuators. First, the individual elements of the claimed subject matter of the invention are explained in the order in which they are mentioned in the claim set, and subsequently, particularly preferred embodiments of the subject matter of the invention are described. The magnetic flux in an electric axial flux machine (AFM), such as an electric drive motor in a motor vehicle designed as an axial flux machine, is directed axially in the air gap between the stator and rotor, relative to the rotational direction of the rotor. There are different types of axial flux machines. One well-known type is the so-called I-arrangement, in which the rotor is arranged axially next to a stator or between two stators. Another well-known type is the so-called H-arrangement, in which two rotors are arranged on opposite axial sides of a stator. The stator of an electric axial flux machine comprises a stator body with several circumferentially arranged stator windings. The stator body can be a single piece or segmented in the circumferential direction. It can be formed from a stator lamination stack consisting of several laminated electrical steel sheets. Alternatively, the stator body can be made of a pressed soft magnetic material, such as SMC (Soft Magnetic Compound). A rotor shaft is a rotatably mounted shaft of an electric machine, to which the rotor or rotor body is coupled in a rotationally fixed manner. The rotor of an electric axial flux machine can be designed, at least in part, as a laminated rotor. A laminated rotor is constructed with layers in the axial direction. The axial magnetic flux must overcome the adhesive or insulating layers between the stacked individual electrical steel sheets, which causes shearing (an additional air gap) in the magnetic circuit and reduces its efficiency. Alternatively, the rotor of an axial flux machine can also have a rotor carrier that is appropriately equipped with magnetic sheets and / or SMC material and with magnetic elements designed as permanent magnets. Advantageous embodiments of the invention are specified in the dependent claims. The features listed individually in the dependent claims can be combined in a technologically meaningful manner and can define further embodiments of the invention. Furthermore, the features specified in the claims are specified and explained in more detail in the description, which also presents further preferred embodiments of the invention. According to an advantageous embodiment of the invention, the adjusting device may comprise at least one spring assembly which acts on the first and second partial stator against the magnetic attraction between the rotor body and the stator, wherein the spring assembly is configured such that a spring force characteristic is formed which lies above the magnetic force characteristic over the entire adjustment range. The advantage of this embodiment is that a mechanical adjusting unit can be used which only needs to operate under pressure (e.g., a wedge) and the force that must be overcome by this unit is significantly reduced. According to a further preferred embodiment of the invention, the spring assembly may also comprise a first spring element, a second spring element, and a third spring element, wherein the first spring element is configured as an axially centrally arranged leaf spring assembly with a plurality of individual leaf spring assemblies, and wherein the second spring element is configured as a disc spring arranged axially between the first spring element and the first partial stator, and wherein the third spring element is configured as a disc spring arranged axially between the first spring element and the second partial stator. This allows the system to optimally follow the given magnetic force of the system, which is non-linear, at a predetermined distance. Furthermore, according to another advantageous embodiment of the invention, the first, second, and third spring elements can be arranged mechanically in series such that, over a first adjustment travel section, both the first spring element and the second and third spring elements are compressed, at least partially but not completely, and that within a second adjustment travel section following the first adjustment travel section, the first spring element remains completely compressed, while the second and third spring elements continue to be compressed. The advantageous effect of this embodiment is that, in addition to optimizing the spring force distribution compared to the magnetic force specified by the system, improved strength of the entire spring assembly can be achieved. According to a further particularly preferred embodiment of the invention, the first partial stator may have a cup-shaped stator support which receives a first stator lamination stack in a cup-like recess and which has a radially outwardly directed annular collar at the free end of its axially extending annular (hollow cylindrical) side wall, and the second partial stator may have a cup-shaped stator support which receives a second stator lamination stack in a cup-like recess and which has a radially outwardly directed annular collar at the free end of its annular (hollow cylindrical) side wall. The first and second stator supports are essentially identical in design and arranged in a mirror-symmetrical manner. The spring assembly is also annular in shape and is arranged between the annular collars of the first and second partial stator.This achieves the particular effect that the compensating forces are supported between the stators rotating together, thus avoiding the need for an additional, heavily loaded bearing. This simplifies the design and reduces costs. Advantageously, each stator lamination stack is fastened in the pot-shaped stator carrier by means of pin-shaped fasteners. Particularly preferably, the fasteners are positioned or arranged such that, viewed axially, each fastener divides the annular area (Ages) of the respective stator sub-stem into an inner sub-stem (Ainner) and an equally sized outer sub-stem (Aouter). The annular areas are, in particular, oriented perpendicular to the rotational axis of the rotor body. This ensures that the fastening is located precisely at the theoretical point of application of the magnetic force, thus eliminating any lever arm that would place additional stress on the stator stack. According to a further preferred embodiment of the invention, the axial flux machine may have a housing in which the rotor shaft is arranged axially on both sides via a rotor shaft receptacle within a motor housing. Advantageously, each rotor shaft receptacle receives the rotor shaft on one axial side via a bearing, particularly with rolling elements, and is supported against or fixedly mounted in a housing wall of the motor housing on its other axial side. The combination of motor bearing and adjustment mechanism thus enables a compact design. Finally, the invention can also be advantageously implemented such that axial adjustment means (for example, in the form of insertable annular spacer or shim discs) are provided for the axial centering of the rotor relative to the stator, by means of which the rotor with its rotor body can be axially positioned relative to the axially adjacent sub-stators. This allows a kind of basic adjustment or center positioning of the central rotor body relative to the two axially adjacent sub-stators to be carried out during manufacturing using structurally simple means. The axial flux machine according to the invention is characterized in that the adjustment device comprises a first adjustment unit assigned to the first sub-stator and a second adjustment unit assigned to the second sub-stator, each of the two adjustment units comprising an axially externally arranged, stationary adjustment element, in particular one which is rotationally and slidably connected to the respective rotor shaft mount, and an axially internally arranged adjustment element which is axially displaceable and at least partially rotatable relative to the outer stationary adjustment element and is rigidly connected to the sub-stator assigned to it. At least one rolling element is arranged between the stationary adjustment element and the axially displaceable adjustment element.Furthermore, the stationary adjusting element has a first ramp element on its side facing the movable adjusting element, and the movable adjusting element has a second ramp element on its side facing the stationary adjusting element. The first and second ramp elements are designed such that, in the event of rotation of the first adjusting element relative to the second adjusting element or vice versa, the respective sub-stator is axially displaced relative to the rotor shaft, thereby reducing the axial extent of the air gap formed between the respective sub-stator and the rotor body. This enables, with simple design features, a reliable torque-dependent adjustment of the air gaps formed between the rotor body and the sub-stators, and thus a reliable field weakening or strengthening of the electric machine.Preferably, the two sub-stators are arranged in a floating manner on the rotor shaft or on a rotor shaft receptacle, and the two sub-stators support each other via the adjustment device, so that separate additional support means can be omitted or are not required. Advantageously, the spring assembly is designed such that it produces a spring force characteristic that lies above a function Fmagnet_limit = Fmagnet + Fmagnet_max* over the entire adjustment range – in other words, the spring force is slightly above the magnetic attraction between the rotor and the sub-stators over the entire adjustment range, so that only very small forces are required to adjust the two sub-stators. The first spring element is particularly preferably designed to produce a linear spring force characteristic. The second and third spring elements are advantageously designed to produce a progressive spring force characteristic. Preferably, lashing elements are provided between the first and second adjusting elements. These lashing elements are designed such that, in an operating condition with a predetermined torque exceeding a predetermined maximum adjusting torque, the resulting torque is transmitted via the lashing elements instead of via the corresponding first and second ramp elements of the first and second adjusting elements. This has the advantage of relieving the ramp structure of support forces. The first and second stators are preferably rotationally coupled to each other such that no relative rotation occurs between them during operation of the axial flux machine. This can be achieved by a frictional connection between the two rotor bodies via the spring assembly located between the first and second stators, or alternatively, by a connecting element for rotational coupling between the spring assembly and each stator. The first spring element particularly preferably comprises at least six leaf spring assemblies, an annular support ring, and two spring support rings, wherein three leaf spring assemblies are arranged on each side, evenly distributed around the circumference, between the axially centrally arranged support ring and each axially adjacent spring support ring.This creates a structurally space-saving and structurally simple central spring element. In particular, the spring assembly is designed such that the two spring support rings, arranged axially spaced from the central support ring and rigidly connected on both sides to the respective individual leaf spring assemblies, rotate in the same direction over the entire axial adjustment range without any relative rotational offset. Each of the individual leaf spring assemblies is rigidly connected to the support ring at one free end and to the spring support ring, which is axially spaced from the support ring via the individual leaf spring assemblies, at its other free end.Advantageously, the spring assembly is designed such that the two spring support rings, arranged axially spaced from the support ring and firmly connected on both sides to the respective individual leaf spring assemblies, rotate in the same direction over the entire adjustment range and without any relative rotational offset to each other. This creates a spring assembly which, due to its scissor-joint design, prevents relative rotation and thus circumferential tension between the two axially spaced spring support rings when the spring assembly is compressed and subsequently released over the entire adjustment range. In summary, the magnetic force between the rotor and stator changes depending on the width of the air gap, so the spring force of the compensating spring must also change along the adjustment path. To minimize the force on the adjustment unit, the force difference between the two characteristic curves must be kept as small as possible. However, it is important to ensure that the spring force is always greater than the magnetic force to maintain a preload on the adjustment unit. The adjustment is achieved by the applied torque in the electric motor, which, via a ball ramp in the adjustment unit, generates an additional axial force that leads to the axial adjustment. In the proposed design, a constant ramp slope, and thus two end positions of the adjustment, are implemented. However, it would also be conceivable to implement several intermediate layers if the ramp gradient is variable via the angle of rotation. In the initial and intermediate positions, the moment is supported via the ramp system, as otherwise no adjustment would be possible. In the end position, which is used for high moments in the electric machine, an additional connection between the ramps is preferably implemented to support the high applied moments. This rotational support should have finite stiffness. Overall, the system described above works in such a way that the spring forces required for both sides mutually support each other. This means that no internal force support via an additional bearing is necessary. Another advantage is that the two ramp sides are coupled in the direction of rotation via the frictional force of the springs. To achieve the spring characteristic curve within the available installation space, two individual springs are required on each side. For the long but nearly constant rise at the beginning of the adjustment, leaf spring assemblies are used on both sides. These leaf spring assemblies are self-limiting after a certain travel distance, as they are compressed into a single block. This self-limiting mechanism protects them from overload. For the leaf springs to be connected to the same support component on both sides, they must have the same geometry (hole spacing, thickness, mounting height, bolt circle diameter, etc.). However, a condition for this is that they must be oriented in opposite directions. This means that when the springs change their axial height during operation, the resulting radial displacement must be the same in magnitude and in the same direction. If this is not the case, the leaf springs will build up an internal torque that inhibits adjustment and places high stress on the components. On the other hand, the use of leaf springs also provides centering for the spring assembly itself. Once the leaf springs are compressed, meaning they no longer exhibit any spring characteristics, the disc springs, which are also installed, take over for the final part of the characteristic curve. In the first part of the characteristic curve, both the disc springs and the leaf springs are active, but since the disc springs are much stiffer than the leaf springs, they have little influence on the overall stiffness at the beginning of the characteristic curve. The spring and magnetic forces intended for the function are shown in the diagram in Fig. 5. To position the characteristic curves accurately and with minimal influence from tolerances, it can be advantageous to adjust the height of the adjustment unit using shims during assembly. The proposed design allows this, as the interfaces are chosen so that the height can be adjusted at various points. This can be done, for example, under the ramp units or under the outer retaining ring of the bearing shaft. In the illustrations shown, these shims are arranged under the stationary ramp elements. Another advantage of the design shown is that the large magnetic forces, which in this motor variant must generally be supported by the outer bearings, are significantly reduced by the internal support of the forces. This means that the outer bearing design can be less complex (the bearings can be smaller). The invention and its technical context are explained in more detail below with reference to the figures. It should be noted that the invention is not limited to the embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract aspects of the concepts illustrated in the figures and combine them with other elements and findings from the present description and / or figures. It should be emphasized that the figures, and especially the depicted dimensions, are only schematic. Identical reference numerals denote the same objects, so that explanations from other figures may be consulted for further clarification. Figure 1 shows an axial flux machine according to the invention in an I-arrangement in one possible embodiment, in an axial section, in a schematic representation, in a field-strengthened operating position with the smallest possible air gaps between the centrally arranged rotor body and the axially adjacent sub-stators; Figure 2 shows the axial flux machine according to Figure 1, in a field-weakened operating position with the largest possible air gaps between the centrally arranged rotor body and the axially adjacent sub-stators; Figure 3 shows a central first spring element of a spring assembly of the adjustment device according to the invention in a perspective view; Figure 4 shows an adjustment unit of the adjustment device according to the invention in a perspective view; and Figure 5 shows...5 two different force characteristics over the adjustment path of the adjustment device according to the invention, wherein the lower characteristic curve shows the force curve of the magnetic force prevailing between rotor and stator and wherein the upper characteristic curve shows the force curve of the compensation spring or the spring device. Fig. 1 shows an axial flux machine 1 according to the invention in an I-arrangement, in a possible embodiment of the invention, in an axial section, in a schematic representation. The axial flux machine 1 shown is depicted in a field-strengthened operating position with the smallest possible air gaps L1, L2 between the centrally arranged rotor body 31 and the axially adjacent sub-stators 21, 22. The axial flux machine 1 shown, with an integrated torque-dependent adjustment device 4 for adjusting the air gaps between the central rotor body 31 and the two sub-stators 21, 22, which are axially displaceable on both sides, is primarily an arrangement for field strengthening – the field-weakened “rest” or initial state is shown in Fig. 2. The two sub-stators 21, 22 are attracted towards the rotor body 31 by the magnetic attraction forces between rotor 3 and stator 2.The spring assembly 40, arranged between the two partial stators 21, 22, counteracts the magnetic attraction with its force and whose spring force is dimensioned such that it is slightly greater than the magnetic force between stator 2 and rotor 3 over the entire adjustment range, pushes the two partial stators 21, 22 away from the rotor body 31 (i.e., pushes them apart). Thus, the (initially large) air gaps L1, L2 (see Fig. 2) are reduced during the start-up of the electric machine, where the torque arrangement is usually quite large (see Fig. 1). At higher speeds with lower torque requirements, the air gaps L1, L2 are automatically increased again by the spring assembly (see Fig. 2), ensuring operation of the electric machine 1 with lower losses. Fig. 2 shows the axial flux machine 1 according to Fig. 1, in a field-weakened operating position (e.g. rest position) with the largest possible air gaps L1, L2 between the centrally arranged rotor body 31 and the axially adjacent partial stators 21, 22. Figures 1 and 2 each show an electric axial flux machine 1, comprising a stator 2 with a first sub-stator 21 and a second sub-stator 22 arranged axially spaced from the first sub-stator 21, and a rotor 3 with a disk-shaped rotor body 31 mounted on a rotor shaft 30 and arranged axially between the first sub-stator 21 and the second sub-stator 22. The first sub-stator 21 and the second sub-stator 22 are arranged to be movable in the axial direction relative to the rotor body 31. Furthermore, an adjusting device 4 is provided for adjusting the air gaps L1, L2 between the central rotor body 31 and the two adjacent sub-stators 21, 22, which are arranged to be axially displaceable. The adjusting device 4 is configured to displace the first sub-stator 21 and the second sub-stator 22 in the axial direction to adjust an air gap L1, L2.The adjusting device 4 is configured to adjust the first sub-stator 21 and the second sub-stator 22 in the axial direction depending on a torque transmitted via the rotor shaft 3, which generates a supporting torque resulting on the first sub-stator 21 and the second sub-stator 22. The adjusting device 4 comprises at least two adjusting units 51, 52 designed as a ball-ramp system, with each sub-stator 21, 22 being assigned one adjusting unit 51, 52, and further comprises a spring device 40 arranged between the two sub-stators 21, 22, which, in the present embodiment, pushes the two sub-stators 21, 22 apart to weaken the field at low torque requirements of the electric machine, thus increasing the air gaps L1, L2. The spring assembly 40 is configured such that a spring force characteristic KL2 is formed which lies above the magnetic force characteristic KL1 over the entire adjustment range V. Figures 1 and 2 clearly show that the spring assembly 40 comprises a first spring element 400, a second spring element 401, and a third spring element 402, wherein the first spring element 400 is designed as an axially centrally arranged leaf spring assembly with a plurality of individual leaf spring assemblies 41a, 42a, and wherein the second spring element 401 is designed as a disc spring arranged axially between the first spring element 41, 42 and the first partial stator 21, and wherein the third spring element 402 is designed as a disc spring arranged axially between the first spring element 400 and the first partial stator 21.The first spring element 400, the second spring element 401 and the third spring element 402 are mechanically arranged in series such that over a first adjustment travel section both the first spring element 400 and the second and third spring elements 401, 402 are at least partially but not completely compressed and that within a second adjustment travel section following the first adjustment travel section, the first spring element 400 remains completely compressed. The first partial stator 21 has a cup-shaped stator support 210, which receives a first stator lamination stack 211 in a cup-like recess and has a radially outwardly directed annular collar 210a at the free end of its axially extending annular side wall. Similarly, the second partial stator 22 also has a cup-shaped stator support 220, which receives a second stator lamination stack 221 in a cup-like recess and has a radially outwardly directed annular collar 220a at the free end of its annular side wall. The first stator support 210 and the second stator support 220 are essentially identical in design and arranged symmetrically to each other. The spring assembly 40, arranged between the annular collars 210a, 22a of the two stator supports 21, 22, is annular in shape. The respective lamination stack of the stator 2 is fastened in the pot space of the respective pot-shaped stator support 210, 220 by means of fastening means 212, 222 designed as screws. Particularly preferably, the fastening means 212, 222 are positioned or arranged such that, viewed radially, the fastening means 212 of the first partial stator 21 and the fastening means 222 of the second partial stator 22 are arranged such that, viewed axially, the respective fastening means 212; 222 divide the annular surface Ages of the partial stator 21; 22, arranged perpendicular to the axis of rotation of the rotor body 31, into an inner partial annular surface Ainner and an equally sized outer partial annular surface AOuter. The axial flux machine 1 has a housing 100, wherein the rotor shaft 30 is arranged axially on both sides within a motor housing 100 via rotor shaft mounts 301, 302. Each rotor shaft mount 301, 302 receives the rotor shaft 3 (or a shaft section of the rotor body 31) on one axial side via a bearing with rolling elements W, while the rotor shaft mount 301, 302 is supported against or fixedly mounted in a housing wall of the motor housing 100 on its other axial side. For the axial centering of the rotor 3 relative to the stator 2, axial adjusting means 7, such as shims or the like, are provided, by means of which the rotor 3 with its rotor body 31 can be axially positioned relative to the axially adjacent partial stators 21, 22.The adjusting device 4 itself comprises a first adjusting unit 51, associated with the first sub-stator 21, and a second adjusting unit 52, associated with the second sub-stator 22. Each of the two adjusting units 51, 52 has an axially externally arranged, stationary adjusting element 511, 521, which is connected to the respective rotor shaft receptacle 301, 302 in a rotationally and slidably fixed manner, and an axially internally arranged adjusting element 512, 522, which is axially displaceable and at least partially rotatable relative to the outer stationary adjusting element 511, 521 and is rigidly connected to the sub-stator 21, 22 associated with it. At least three rolling elements W are arranged circumferentially distributed between the stationary adjusting element 511, 521 and the axially displaceable adjusting element 512, 522. As shown in Fig.As shown in Figure 4, the stationary adjusting element 511, 521 has a first ramp element R1 on its side facing the movable adjusting element 512, 522, and the movable adjusting element 512, 522 has a second ramp element R2 on its side facing the stationary adjusting element 511, 521, wherein the first ramp element R1 and the second ramp element R2 are designed such that, in the event of a rotation of the first adjusting element R1 relative to the second adjusting element R2 or vice versa, the respective associated sub-stator 21, 22 is axially displaced relative to the rotor shaft 3, such that the air gap L1; L2 formed between the respective sub-stator 21, 22 and the rotor body 31 is reduced or increased in its axial extent. Due to the design, the two sub-stators 21, 22 are floatingly mounted on the rotor shaft 30 and on the rotor shaft receptacles 301, 302, respectively. Furthermore, the two sub-stators 21, 22 mutually support each other via the adjustment device 4. The spring assembly 40 is designed to exhibit a spring force characteristic KL2 that lies below the function Fmagnet_limit = Fmagnet + Fmagnet_max*0.3 over the entire adjustment range. For this purpose, the first spring element 400 is designed to exhibit a linear spring force characteristic, while the second and third spring elements 401, 402 are designed to exhibit a progressive spring force characteristic. Between the first adjusting element 511, 521 and the second adjusting element 512, 522, (rotationally acting) lifting means A1, A2 are provided, which are designed such that in an operating condition with a predetermined torque which is above a predetermined maximum adjusting torque, the occurring torque is transmitted via the lifting means A1, A2 instead of via the corresponding first and second ramp means R1, R2 of first and second adjusting element 51; 52. For this purpose, the first adjusting element 511, 521 has two radially outwardly directed stop segments which interact with stop elements formed in the axial direction on the second adjusting element 512, 522. The first sub-stator 21 and the second sub-stator 22 are rotationally coupled to each other in such a way that no relative rotation occurs between the first sub-stator 21 and the second sub-stator 22 during the operation of the axial flux machine 1.For this purpose, a frictional connection between the two rotor bodies 31 and 32 is achieved via the spring assembly 40 arranged between the first and second sub-stator 21 and 22. Alternatively – and not shown here – a connecting element for rotational coupling can be provided between the spring assembly 40 and each sub-stator 21 and 22. Fig. 3 shows a perspective view of a central first spring element 400 of a spring assembly 40 of the adjusting device 4 according to the invention. As shown in Fig. 3, the first spring element 400 comprises a total of six leaf spring assemblies 41a, 42a, an annular support ring T, and two spring support rings T1, T2. Three leaf spring assemblies 41a, 42a are arranged circumferentially and uniformly on each side between the axially centrally arranged support ring T and each of the axially adjacent spring support rings T1, T2. The two spring support rings T1, T2, which are arranged axially spaced from the central support ring T and are rigidly connected on both sides to the respective leaf spring assemblies 41a, 42a, rotate in the same direction over the entire axial adjustment range V and without any relative rotational offset from each other.The spring assembly shown thus has an overall scissor-joint-like structure, which prevents relative rotation and thus circumferential tension between the two axially spaced spring support rings when the spring assembly is compressed and subsequently relaxed over the entire adjustment range. Fig. 5 shows two different force characteristics KL1, KL2 over the adjustment path V of the adjustment device 4 according to the invention, wherein the lower characteristic KL1 shows the force curve of the magnetic force prevailing between rotor 3 and stator 2 and wherein the upper characteristic KL2 shows the force curve of the compensation spring or the spring device 40. The invention is not limited to the embodiments illustrated in the figures. The foregoing description is therefore not to be considered limiting, but rather explanatory. The following claims are to be understood as meaning that a named feature is present in at least one embodiment of the invention. This does not preclude the presence of further features. Insofar as the claims and the foregoing description define 'first' and 'second' features, this designation serves to distinguish between two similar features without establishing any hierarchy. Reference symbol list 1 Axial flux machine 100 Housing 2 Stator 21 Partial stator 210 Stator support 210a Ring collar 211 Stator lamination stack 22 Partial stator 212 Fastening means 220 Stator support 220a Ring collar 221 Stator lamination stack 222 Fastening means 3 Rotor 30 Rotor shaft 301 Rotor shaft mount 302 Rotor shaft mount 31 Rotor body 4 Adjustment device 40 Spring device 400 First spring element 401 Second spring element 402 Third spring element 41 Leaf spring individual packs 42 Spring element 5 Adjustment unit 51 First adjustment unit 511 Adjustment element 512 Adjustment element 52 Second adjustment unit 521 Adjustment element 522 Adjustment element 7 Axial adjustment means Ages annular surface A inner inner partial annular surface A outer outer partial annular surface W Rolling element R1 First ramp element R2 second ramp element L1 air gap L2 air gap A1 lifting device A2 lifting device T support ring T1 spring support ring T2 spring support ring V adjustment range x1 first adjustment range section x2 second adjustment range section KL1Force-displacement characteristic of the magnetic force over the adjustment range KL2; force-displacement characteristic of the spring device over the adjustment range

Claims

An electric axial flux machine (1) comprising: a stator (2) with a first partial stator (21) and with a second partial stator (22) arranged axially spaced from the first partial stator (21), and a rotor (3) with a disk-shaped rotor body (31) arranged on a rotor shaft (30) and axially positioned between the first partial stator (21) and the second partial stator (22), wherein the first partial stator (21) and the second partial stator (22) are arranged to be movable in the axial direction relative to the rotor body (31), and an adjusting device (4) which is configured to adjust the first partial stator (21) and the second partial stator (22) in the axial direction to set an air gap (L1, L2) and depending on a torque to be transmitted via the rotor shaft (3), which generates a supporting torque resulting on the first partial stator (21) and on the second partial stator (22). adjust, wherein the adjusting device (4) is a first,a first adjusting unit (51) associated with the first partial stator (21) and a second adjusting unit (52) associated with the second partial stator (22), characterized in that each of the two adjusting units (51; 52) has an axially externally arranged stationary adjusting element (511, 521) and an axially internally located adjusting element (512, 522) which is axially displaceable and at least partially rotatable relative to the externally located stationary adjusting element (511, 521) and is rigidly connected to the partial stator (21, 22) associated with it, and that at least one rolling element (W) is arranged between the stationary adjusting element (511, 521) and the axially displaceable adjusting element (512, 522), and that the stationary adjusting element (511, 521) is on its axially displaceable side relative to the axially displaceable adjusting element (512, 522). The adjusting element (512, 522) has a first ramp element (R1) on its side facing the adjusting element (512, 522) and the movable adjusting element (512, 522) is on its side facing the stationary adjusting element (511,521) has a second ramp element (R2) on the side facing the rotor shaft (31), and the first ramp element (R1) and the second ramp element (R2) are designed such that, in the event of a rotation of the first adjusting element (R1) against the second adjusting element (R2) or vice versa, the respective associated partial stator (21, 22) is axially displaced relative to the rotor shaft (3) in such a way that the air gap (L1; L2) formed between the respective partial stator (21, 22) and the rotor body (31) is reduced in its axial extent. Axial flux machine (1) according to claim 1, characterized in that the adjusting device (4) comprises at least one spring device (40) which acts on the first partial stator (21) and on the second partial stator (22) against the magnetic attraction force between rotor body (31) and stator (2), and the spring device (40) is configured such that a spring force characteristic (KL2) is formed which runs above the magnetic force characteristic (KL1) over the entire adjustment path (V). Axial flux machine (1) according to claim 2, characterized in that the spring assembly (40) comprises a first spring element (400), a second spring element (401) and a third spring element (402), the first spring element (400) is designed as an axially centrally arranged leaf spring assembly with a plurality of individual leaf spring assemblies (41a, 42a), the second spring element (401) is designed as a disc spring arranged axially between the first spring element (41, 42) and the first partial stator (21), and the third spring element (402) is designed as a disc spring arranged axially between the first spring element (400) and the second partial stator (22). Axial flux machine (1) according to claim 3, characterized in that the first spring element (400), the second spring element (401) and the third spring element (402) are mechanically arranged in series such that over a first adjustment travel section (x1) both the first spring element (400) and the second and third spring elements (401, 402) are at least partially but not completely compressed and that within a second adjustment travel section (x2) following the first adjustment travel section (x1) the first spring element (400) remains completely compressed. Axial flux machine (1) according to one of claims 2 to 4, characterized in that the first partial stator (21) has a pot-shaped stator support (210) which receives a first stator lamination stack (211) in a pot-shaped recess and which has a radially outwardly directed annular collar (210a) at the free end of its axially extending annular side wall, the second partial stator (22) has a pot-shaped stator support (220) which receives a second stator lamination stack (221) in a pot-shaped recess and which has a radially outwardly directed annular collar (220a) at the free end of its annular side wall, the first stator support (210) and the second stator support (220) are essentially identical in design and arranged in a mirror-symmetrical manner, and the spring assembly (40) is annular in shape and is located between the annular collars (210a, 220a) of the first partial stator (21) and the second stator support (220). is arranged in the second substator (22). Axial flux machine (1) according to one of claims 1 to 5, characterized in that the respective stator lamination stack (211, 221) of the respective partial stator (21, 22) is fastened in the pot space of the respective pot-shaped stator support (210, 220) via pin-shaped fastening means (212, 222). Axial flux machine (1) according to claim 6, characterized in that the fastening means (212) of the first partial stator (21) and the fastening means (222) of the second partial stator (22) are arranged in a radial direction such that, in an axial direction, the fastening means (212; 222) divides the annular area (Ages) of the partial stator (21; 22) into an inner partial annular area (Ainner) and an outer partial annular area (AOuter) of the same size. Axial flux machine (1) according to claim 6 or 7, characterized in that the fastening means (212; 222) are formed by screws or rivets for fastening the stator lamination stack (211, 221) to the respective stator support (210, 220). Axial flux machine (1) according to one of claims 1 to 8, characterized in that the axial flux machine (1) has a housing (100) and the rotor shaft (30) is arranged axially on both sides via a rotor shaft receptacle (301, 302) within a motor housing (100), advantageously each rotor shaft receptacle (301, 302) receives the rotor shaft (3) on one axial side via a bearing and the rotor shaft receptacle (301, 302) is supported against a housing wall of the motor housing (100) or is firmly received in it on its other axial side. Axial flux machine (1) according to one of claims 1 to 9, characterized in that axial adjusting means (7) are provided for the axial centering of the rotor (3) relative to the stator (2), by means of which the rotor (3) with its rotor body (31) can be axially positioned relative to the axially adjacent partial stators (21, 22). Axial flux machine (1) according to one of claims 1 to 10, characterized in that the two partial stators (21, 22) are arranged floatingly on the rotor shaft (30) or on a rotor shaft receptacle (301, 302) and the two partial stators (21, 22) support each other via the adjusting device (4). Axial flux machine (1) according to one of claims 2 to 5, characterized in that the spring device (40) is configured to map a spring force characteristic curve which remains below a function F magnet _ limit = F magnet + F magnet _ max * 0.3 over the entire adjustment range. lies. Axial flux machine (1) according to claim 3 or 4, characterized in that the first spring element (400) is configured to represent a linear spring force characteristic and / or the second and third spring elements (401, 402) are configured to represent a progressive spring force characteristic. Axial flux machine (1) according to one of claims 1 to 13, characterized in that stop means (A1, A2) are provided between the first adjusting element (511, 521) and the second adjusting element (512, 522), which are designed such that in an operating state with a predetermined torque which is above a predetermined maximum adjusting torque, the torque occurring is transmitted via the stop means (A1, A2) instead of via the corresponding first and second ramp means (R1, R2) of first and second adjusting element (51; 52). Axial flux machine (1) according to one of claims 2 to 5, 12 or 13, characterized in that the first partial stator (21) and the second partial stator (22) are rotationally coupled to each other, such that during operation of the axial flux machine (1) no relative rotation occurs between the first partial stator (21) and the second partial stator (22), preferably a frictional connection between the two rotor bodies (31; 32) is realized via the spring device (40) arranged between the first and second partial stator (21; 22) or preferably a connecting element for rotational coupling is provided between the spring device (40) and each partial stator (21, 22). Axial flux machine (1) according to claim 3 or 4, characterized in that the first spring element (400) comprises at least six leaf spring individual packages (41a, 42a) as well as an annular support ring (T) and two spring support rings (T1, T2), and between the axially centrally arranged support ring (T) and each axially adjacent support ring (T1, T2), three leaf spring packages (41a, 42a) are arranged on each side, distributed uniformly around the circumference. Axial flux machine (1) according to claim 16, characterized in that the spring device (40) is constructed such that the two spring support rings (T1, T2) arranged axially spaced from the central support ring (T) and firmly connected on both sides to the respective leaf spring individual packages (41a, 42a) move rotationally in the same direction and without a relative rotational offset to each other over the entire axial adjustment path (V).

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