Stator for an electric axial flux machine and electric axial flux machine

Abstract

The invention relates to a stator (1) for an electric axial flux machine (2), more particularly to a stator (1) for an axial flux machine (2) designed as a prime mover for electrically driven motor vehicles, comprising a stator body (10) having a plurality of stator teeth (11) distributed around a circumference and a stator winding (3). According to the invention, at least one of the wound stator teeth (11) is divided into at least two stator partial teeth (111, 112, 113, 114) viewed in the radial direction, wherein the at least two stator partial teeth (111; 112) are wound with different numbers of turns of the stator winding (3).

Description

TECHNICAL FIELD

[0001] The invention relates to a stator for an electric axial flux machine, in particular to a stator for a permanent-magnetic axial flux machine designed as a prime mover for electrically driven motor vehicles, comprising a stator body having a plurality of stator teeth distributed around a circumference, and stator windings arranged around the stator teeth, which are advantageously wound around the plurality of stator teeth and are respectively designed as single-tooth-integrated windings. Furthermore, the invention relates to an electric axial flux machine. BACKGROUND

[0002] Axial flux machines are already known in the prior art.

[0003] 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 mounted in a rotatable manner in a bearing, and wherein the stator segments are arranged in an immovable manner with respect to the bearing in the direction of rotation of the rotor. At least one of the stator segments is arranged to be movable in an axial or radial direction with respect to the bearing in order to adjust the width of the air gap between the rotor and the stator segments. SUMMARY

[0004] The invention is based on the object of providing a stator for an axial flux machine, in which the maximum electrical load in the stator is increased compared to a stator of the same size. Furthermore, the invention is based on the object of providing a corresponding axial flux machine, in which the maximum electrical load within the stator is increased. For a given number of stator teeth in the axial flux machine, each stator tooth has a fixed angular range. This means that a radially more inward region of the stator teeth can be provided with a smaller circumferential length than a radially more outward region. The available circumferential length is divided between the magnetic flux conducting elements, the windings, the insulation, etc. In the prior art, the windings and the insulation usually have a constant cross section along the winding around the magnetic flux conducting elements. Therefore, the windings and the insulation require an increasing angular range for smaller radii, while an increasing smaller angular range is available for the magnetic flux conducting elements. In order not to fall below the minimum width of the magnetic flux conducting elements, the circumferential width and thus the cross section of the windings and the insulation is limited.

[0005] The object of the invention is achieved by a stator for an electric axial flux machine, in particular a permanent-magnetic axial flux machine, having the features of claim 1, and by an electric machine having the features of claim 11.

[0006] The electric axial flux machine according to the present application comprises a stator body having a plurality of stator teeth distributed around a circumference and stator windings (3) arranged around the stator teeth (11).

[0007] At least one of the winding stator teeth, preferably all stator teeth, is divided into at least two stator partial teeth in the radial direction, wherein the at least two stator partial teeth are wound with stator windings of different number of turns. Particularly preferably, two stator partial teeth are wound with stator windings of different number of turns of the same phase. Advantageously, the at least two stator partial teeth are spaced apart in the radial direction by a separating groove extending in the circumferential direction and formed at an axial depth. As proposed by the present application, by separating the stator teeth and the windings, more winding cross sections can be arranged in a radially more outer region of the stator without the tooth width in the radially more inner region of the stator necessarily being disadvantageously smaller in the circumferential direction. In the present exemplary embodiment, the stator body is formed as a segmented stator body, wherein a plurality of stator segments or individual stator teeth are assembled circumferentially to form a circular ring-shaped stator body. Alternatively, the stator body can also be formed as a one-piece.

[0008] First, the individual elements of the subject matter claimed in the present application are described in the order in which the individual elements are mentioned in the claim set, and then a particularly preferred embodiment of the subject matter of the present application is described.

[0009] The magnetic flux in electric axial flux machines (AFM), such as electric prime movers of motor vehicles designed as axial flux machines, is directed axially in the direction of rotation of the rotor of the axial flux machine in the air gap between the stator and the rotor. There are different types of axial flux machines. One well-known type is the so-called I-type arrangement, in which the rotor is arranged axially close to the stator or between two stators. Another well-known type is the so-called H-type arrangement, in which two rotors are arranged on opposite axial sides of the stator.

[0010] The stator of the electric axial flux machine has a stator body with a plurality of stator windings arranged in the circumferential direction. The stator body can be formed as a one-piece or segmented in the circumferential direction. The stator body can be formed from a stator lamination core having a plurality of laminated electrical sheets. Alternatively, the stator body can also be formed from a compressed soft magnetic material, such as a so-called SMC (soft magnetic compound) material.

[0011] The rotor shaft is the rotatably mounted shaft of the electric machine, to which the rotor or rotor body is coupled in a non-rotatable manner.

[0012] The rotor of an electric axial flux machine can be designed at least partially as a laminated rotor. Laminated rotors are designed in layers in the axial direction. The axial magnetic flux has to overcome the adhesive or insulation layer between the individual electrical sheets of the stack, which causes the magnetic circuit to experience a shear (additional air gap) and lose efficiency. Alternatively, the rotor of an axial flux machine can also have a rotor carrier which is correspondingly equipped with magnetic sheets and / or SMC material and with magnetic elements designed as permanent magnets.

[0013] Advantageous embodiments of the application are specified in the dependent claims. Features listed individually in the dependent claims can be combined with one another in a technically meaningful manner and can define further embodiments of the application. In addition, features indicated in the claims are specified and explained in more detail in the description, in which further preferred embodiments of the application are shown.

[0014] According to an advantageous embodiment of the application, it can be provided that each of the actually wound stator teeth is observed in the radial direction to be divided into at least two stator partial teeth, whereby the optimized winding cross section of the axial flux machine is fully utilized.

[0015] According to a further preferred further development of the application, it can also be provided that the stator winding of the stator teeth is subdivided into at least two subgroups. A first subgroup of the stator winding encloses the radially outermost stator partial tooth and each further subgroup additionally encloses in each case the next stator partial tooth arranged radially in the direction of the stator center axis X, wherein the last subgroup encloses all stator partial teeth. This allows the winding of the stator teeth, especially in the radially outer region, with a high winding cross section to be particularly efficient without having to design the magnetic flux conducting elements in the radially inner region to be disadvantageously narrow. This allows a more constant ratio of winding cross section to magnetic flux conducting material to be achieved over different diameters.

[0016] As an alternative to the winding type of the stator teeth described above, it can be provided that the stator winding of the stator teeth is subdivided into subgroups, wherein a first subgroup encloses the stator partial teeth arranged between the radially outermost stator partial tooth and the radially innermost stator partial tooth, and each further subgroup additionally encloses in each case the next stator partial tooth arranged in each case radially in the direction of the stator center axis X and / or in the direction radially away from the stator center axis X. This can reduce torque fluctuations during operation, for example due to pole grids (similar to interleaving the magnets with respect to the winding slots). In addition, the ohmic losses and the associated heating can be concentrated in particular in defined regions of the stator.

[0017] According to a further particularly preferred embodiment of the application, it can be provided that the separating grooves formed between the stator part teeth are formed as circular arcs centered on the stator center axis X or as circular arcs centered outside the stator center axis X or as straight lines as secants of a circle and form a polygonal shape. In particular, this improves the mountability of the winding. Furthermore, unnecessary bending of the winding head can be avoided, thus optimizing the electrical resistance.

[0018] Furthermore, the application can be further improved in that the pole shoe cover is attached in a detachable manner at the end face of the free axial end of each stator part tooth in the form of a single piece extending over all stator part teeth. The closed pole shoe cover increases the strength of the stator and a more favorable magnetic flux is achieved in the air gap.

[0019] In a further development of the pole shoe cover, it can be provided that a partial region of each stator part tooth extending in the axial direction is formed on the pole shoe cover, wherein the partial region of the stator part tooth on the pole shoe cover interacts with the partial region of the stator part tooth in a form-fitting manner such that a form fit is ensured in the circumferential direction or tangential direction for torque transmission.

[0020] This allows the circumferential forces to be transmitted from the pole shoe cover to the stator in a particularly simple and robust manner.

[0021] It can also be advantageous to further develop the application in that, viewed in the radial direction, one layer or at most two layers of a sub-group of the stator winding are arranged in the at least one separating groove of the stator part tooth one above the other. This can serve to promote the local cooling of the winding in a targeted manner.

[0022] According to a further preferred embodiment of the subject matter of the application, it can be provided that the stator is designed to operate the electric machine in an H-arrangement, wherein the rotor body is arranged axially on two sides, wherein the stator body is preferably designed to be mirror-symmetrical with respect to a plane perpendicular to the machine rotation axis.

[0023] Furthermore, the object of the application is achieved by an electric axial flux machine comprising at least one stator and a first rotor body arranged on a rotor shaft, or comprising a stator and a first rotor body arranged on a rotor shaft and a second rotor body arranged on a rotor shaft, wherein at least one stator of the machine is designed according to the above-described stator. This provides an electric axial flux machine which realizes an optimized winding cross section of the stator teeth compared to an axial flux machine of the same size. BRIEF DESCRIPTION OF DRAWINGS

[0024] The present invention and the technical field are explained in more detail below with reference to the drawings. It should be noted that the present invention is not intended to be limited by the exemplary embodiments shown. In particular, aspects of the essential subject matter outlined in the summary can be extracted and combined with other parts and knowledge from the description and / or the drawings, unless explicitly stated otherwise. In particular, it should be noted that the drawings and in particular the shown scales are merely schematic. Identical reference signs indicate identical objects, so that the explanations can also be used from other drawings, if applicable.

[0025] In the drawings:

[0026] Figure 1 a schematic perspective view of an axial flux machine in H-arrangement with single tooth windings is shown,

[0027] Figure 2 an axial flux machine according to Figure 1 is shown in a partly exploded view,

[0028] Figure 3 a stator tooth of a stator according to the invention with a segmented stator tooth body (top) and a stator tooth winding (bottom) is shown in a schematic perspective view,

[0029] Figure 4 an axial flux machine in I-arrangement is shown in an exploded view, wherein two stators enclose a rotor centrally located between the two stators and is constructed according to the invention,

[0030] Figure 5 an axial flux machine in I-arrangement is shown in an exploded view, wherein a stator is arranged axially adjacent to a rotor and is constructed according to the invention, and

[0031] Figure 6 a cross-sectional view of a motor constructed similar to the motor in Figure 5 or Figure 1 is shown in the form of a schematic view. DETAILED DESCRIPTION

[0032] Figure 1 a schematic perspective view of an axial flux machine 2 in H-arrangement with single tooth windings is shown. The axial flux machine 2 is shown comprising a stator 1 arranged axially centrally between two rotor bodies 41, 42 arranged on a rotor shaft 4. The stator 1 has a stator body with axially outwardly directed stator teeth 11 on both sides, on which corresponding stator windings 3 are applied in the form of single tooth windings. Bearings are mounted on the rotor shaft 4 axially outside the two rotor bodies 41, 42 to support the electric axial flux machine 2 in a rotatable manner in corresponding bearing receptacles of a housing.

[0033] Figure 2 Fig. 1 shows an axial flux machine 2 according to the present application in a perspective view. The axial flux machine 2 comprises an axially centrally arranged stator 1 having a stator body 10 formed by a plurality of stator teeth 11 distributed around a circumference and stator windings 3 wound around each of the stator teeth 11 and formed as single tooth windings integrated as a winding. Figure 1

[0034] As viewed in the radial direction, each of the wound stator teeth 11 has a total of four stator partial teeth 111, 112, 113, 114, wherein the four stator partial teeth 111, 112, 113, 114 are spaced apart in the radial direction by a separating groove 120 extending in the circumferential direction and formed at an axial depth. In the partial exploded view, it is easily observable that the stator windings 3 can be wound as single tooth windings in a detachable manner from the stator tooth body 11 and applied to the stator tooth body 11 later. The first rotor body 41 and the second rotor body 42 each have a circular ring-shaped carrier plate on which a plurality of permanent magnets in the shape of cake pieces matching the stator teeth 11 are arranged. The rotor bodies 41, 42 are attached to a retaining ring mounted on the rotor shaft 4 in an axially direction in a non-rotatable manner by means of a total of eight circumferentially distributed fastening screws.

[0035] Figure 3 Fig. 2 shows the axial flux machine 2 according to the present application in a schematic perspective view with the stator 1 and the rotor 2 as Figure 4 ​Stator tooth 11 of a segmented stator 1 shown in a sectional view (top) and a stator tooth winding (bottom). It can be clearly observed in this view that the stator tooth 11 has individual stator partial teeth 111, 112, 113, 114, each of which is separated from one another in the radial direction by a separation groove 120 of axial depth extending in the circumferential direction. On the bottom side, the stator partial teeth 111, 112, 113, 114 are connected to one another via a plate-like base portion. In the lower illustration, the structure of the stator winding 3 can be clearly observed, wherein the stator winding is divided into subgroups 31, 32, 33, 34 of winding layers or subwindings. In the present example, each of the stator partial teeth 111, 112, 113, 114 is wound with a different number of turns of the stator winding 3 or with its own subgroup of the stator winding 3. Starting with the radially outer stator partial tooth 111, which is wound with two winding layers (in the separation groove), the next inner stator partial tooth 112 is additionally wound, so that the first stator partial tooth 111 already has four winding layers at the head end at the separation groove 120 and two winding layers at the base end, and the additionally wound second stator partial tooth 112 has two winding layers at the head end in the first separation groove 120 and two winding layers at the base end of the second subgroup 32 of the stator winding 3. In this way, the further two stator partial teeth 113, 114 are also gradually wound so that in the illustrated stator winding 3, exactly two winding layers are arranged in each separation groove 120. Thus, for this type of winding, 4 x 2 winding layers, i.e. at least eight winding layers in total, will be wound on the first stator partial tooth 111 and above the head side in the circumferential direction. In fact, however, the stator tooth 11 has two additional winding layers wrapped around it from the outside, so that here a total of ten winding layers are brought together.

[0036] Figure 4 An axial flux machine 2 in an I-type arrangement is shown in an exploded view, wherein two stators 1 enclose a centrally located rotor body 41, 42 between the two stators and are configured according to the invention. The centrally arranged rotor body 41, 42 has a plurality of permanent magnets distributed in the circumferential direction axially on two sides, each of which interacts with a stator tooth body wound apart by an air gap.

[0037] Figure 5 An axial flux machine 2 is shown in an exploded view, also in an I-type arrangement, wherein only one stator 1 is arranged axially adjacent to the rotor and is configured according to the invention. The stator is configured in the same way as described above.

[0038] Figure 6A cross-sectional view through the electric machine 2 is shown in a schematic drawing. The right drawing shows the cross-sectional plane, while the left drawing shows a top view of the highly schematic cross-sectional plane. The stator 1 is clearly visible, wherein the stator teeth 11 extend axially in the direction of the rotor bodies 41, 42. In this respect, partial areas 21 of the stator teeth 11 are formed on the pole shoe cover 20 to be attached axially at the end face to the stator teeth 11, so that the complete stator teeth 11 are not formed until the pole shoe cover 20 has been installed. In this respect, the pole shoe cover 20 is advantageously attached in a detachable manner at the end face on the free axial end of the individual stator partial teeth 111, 112, 113, 114 in a single piece extending over all stator partial teeth 111, 112, 113, 114. The partial areas 21 of the stator teeth 11 attached to the pole shoe cover 20 interact with the partial areas of the stator partial teeth 111, 112, 113, 114 in a form-fit manner such that a form-fit is ensured in the circumferential direction or tangential direction for torque transmission.

[0039] The present application is not limited to the embodiments shown in the drawings. The above description is therefore to be regarded as explanatory, rather than restrictive. The following claims are to be understood as meaning that the features mentioned are present in at least one embodiment of the present application. This does not exclude the presence of further features. In the case of claims and the foregoing description defining a "first" and a "second" feature, such designation is used to distinguish between two features of the same kind without establishing a priority order.

[0040] Legend of the Figures

[0041] 1 stator

[0042] 2 axial flux machine

[0043] 3 stator winding

[0044] 4 rotor shaft

[0045] 10 stator body

[0046] 11 stator tooth

[0047] 111 stator partial tooth

[0048] 112 stator partial tooth

[0049] 113 stator partial tooth

[0050] 114 stator partial tooth

[0051] 20 pole shoe cover

[0052] 21 partial area of the stator partial tooth (formed on the pole shoe cover)

[0053] 31 stator winding sub-group

[0054] 32 stator winding sub-group

[0055] 33 stator winding sub-group

[0056] 34 stator winding sub-group

[0057] 41 rotor body

[0058] 42 rotor body.

Claims

1. Stator (1) for an electric axial flux machine (2), more particularly for an axial flux machine (2) designed as a prime mover for electrically driven motor vehicles, comprising - a stator body (10) having a plurality of stator teeth (11) distributed around a circumference, and - a stator winding (3) arranged around the stator teeth (11), characterized in that at least one of the stator teeth (11) is divided into at least two stator partial teeth (111, 112, 113, 114) viewed in the radial direction, wherein the at least two stator partial teeth (111; 112) are wound with the same phase of the stator winding (3) with different numbers of turns.

2. Stator (1) according to the preceding claim 1, characterized in that each of the wound stator teeth (11) is divided into at least two stator partial teeth (111; 112) viewed in the radial direction.

3. Stator (1) according to the preceding claim 1 or 2, characterized in that the stator winding (3) of a stator tooth (11) is subdivided into at least two subgroups (31, 32, 33, 34), wherein a first subgroup (31) encloses the radially outermost stator partial tooth (111) and each further subgroup (32, 33, 34) additionally encloses in each case the next stator partial tooth (112, 113, 114) arranged radially in the direction of a stator center axis (X), wherein a last subgroup (34) encloses all stator partial teeth (111, 112, 113, 114).

4. Stator (1) according to the preceding claim 3, characterized in that the stator winding (3) of a stator tooth (11) is subdivided into subgroups (31, 32, 33, 34), wherein a first subgroup (32, 33) encloses the stator partial teeth (112, 113) arranged between the radially outermost stator partial tooth (111) and the radially innermost stator partial tooth (114), and each further subgroup (31, 32, 34; 31, 33, 34) additionally encloses in each case the next stator partial tooth (33, 34, 31; 34, 32, 31) arranged radially in the direction of the stator center axis (X) and / or arranged in the direction away from the stator center axis (X).

5. Stator (1) according to the preceding claim 1 or 2, characterized in that the separating grooves (120) formed between the stator partial teeth (111, 112, 113, 114) are formed as circular arcs centered on the stator center axis (X) or as arcs centered outside the stator center axis (X) or as straight lines forming a polygonal shape.

6. Stator (1) according to the preceding claim 1 or 2, characterized in that The pole shoe cover (20) is attached in a detachable manner at the end faces on the free axial end portions of the individual stator segment teeth (111, 112, 113, 114) in the form of a single piece extending over all the stator segment teeth (111, 112, 113, 114).

7. Stator (1) according to claim 6, characterized in that A partial region (21) of the individual stator segment teeth (111, 112, 113, 114) is formed on the pole shoe cover (20).

8. Stator (1) according to the preceding claim 5, characterized in that At least one of the separation grooves (120) of the stator segment teeth (111, 112, 113, 114) is arranged with a single layer or at most two layers of a sub-group of the stator winding, viewed in the radial direction.

9. Stator (1) according to the preceding claim 1 or 2, characterized in that The stator (1) is designed to operate an electric machine (2) in an H-arrangement, in which rotor bodies (41, 42) are arranged axially on two sides, wherein the stator body (10) is designed to be mirror-symmetrical with respect to a plane perpendicular to the axis of rotation of the electric machine (2).

10. An electric axial flux machine (2) comprising at least one stator (1) and a first rotor body (41; 42) arranged on a rotor shaft (4); or comprising a first rotor body (41) and a second rotor body (42), characterized in that The at least one stator (1) is designed according to any one of the preceding claims.

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