STATOR FOR AN ELECTRIC AXIAL FLUX MACHINE AND ELECTRIC AXIAL FLUX MACHINE

Description

[0001] The present invention relates to a stator for an electric axial flux machine, in particular a stator for a permanently excited axial flux machine designed as a drive motor for an electrically powered motor vehicle, comprising a stator body with a plurality of stator teeth distributed over the circumference and with stator windings arranged around the stator teeth, which are advantageously wound around a plurality of the stator teeth and each configured as a single-tooth concentrated winding. The invention further relates to an electric axial flux machine.

[0002] Axial flux machines are already well known in the state of the art.

[0003] EP 2 985 893 A1 discloses an electric axial flux machine with a stator and a rotor, wherein the stator comprises at least two stator segments, and wherein the rotor is connected to a rotor shaft. The rotor and / or the rotor shaft are rotatably mounted in a bearing, and the stator segments are arranged immovably relative to the bearing in the direction of rotation of the rotor. At least one of the stator segments is arranged 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.

[0004] An electric axial flux machine according to the preamble of claim 1 is known from CN 109 274 240 A.

[0005] The invention is based on the object of providing a stator for an axial flux machine in which the maximum current per unit area is increased compared to stators of the same size. Furthermore, the invention is based on the object of providing a corresponding axial flux machine in which the maximum current per unit area within the stator is increased.

[0006] For a given number of stator teeth in an axial flux machine, a fixed angular range is available for each stator tooth. This means that a smaller circumferential length is available radially further in than in the radially outer areas of the stator teeth. The available circumferential length is divided between the flux guide element, winding, insulation, etc. In the current state of the art, the windings and insulation generally have a constant cross-section along the winding around the flux guide element. As a result, the winding and insulation require an increasingly larger angular range for smaller radii, while an increasingly smaller angular range is available for the flux guide element. In order not to undercut a minimum width of the flux guide elements, the circumferential widths and thus the cross-sections of the winding and insulation are limited.

[0007] The object underlying the invention is achieved by a stator for an electrical axial flux machine, in particular a permanently excited axial flux machine, having the features of patent claim 1 and by an electrical machine having the features of patent claim 10.

[0008] An electric axial flux machine according to the invention comprises a stator body with a plurality of stator teeth arranged distributed over the circumference and stator windings (3) which are arranged around the stator teeth (11).

[0009] At least one of the wound stator teeth - preferably all stator teeth - is / are divided in the radial direction into at least two stator partial teeth, wherein the at least two stator partial teeth are wound with a different number of turns of the stator winding. The two stator partial teeth are wound with a different number of turns of the same phase of the stator winding. Advantageously, the at least two stator partial teeth are spaced apart in the radial direction via a separating groove extending in the circumferential direction and formed in axial depth. Due to the division of the stator teeth and the windings proposed according to the invention, a larger winding cross-section can be arranged in radially outer regions of the stator without the tooth width in radially inner regions of the stator having to be disadvantageously small in the circumferential direction.In the present embodiment, the stator body is formed as a segmented stator body with a plurality of stator segments or individual stator teeth that are circumferentially assembled to form a circular stator body. Alternatively, the stator body can also be formed as a single piece.

[0010] 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, and subsequently, particularly preferred embodiments of the subject matter of the invention are described.

[0011] The magnetic flux in an electric axial flux machine (AFM), such as an electric drive motor of a motor vehicle designed as an axial flux machine, is directed axially in the air gap between the stator and rotor to a rotational direction of the rotor of the axial flux machine. There are different types of axial flux machines. One well-known type is a so-called I-arrangement, in which the rotor is arranged axially next to a stator or between two stators. Another well-known type is a so-called H-arrangement, in which two rotors are arranged on opposite axial sides of a stator.

[0012] The stator of an electric axial flux machine has a stator body with several 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 several laminated electrical sheets. Alternatively, the stator body can also be formed from a pressed soft magnetic material, such as the so-called SMC (Soft Magnetic Compound).

[0013] A rotor shaft is a rotatably mounted shaft of an electrical machine to which the rotor or rotor body is non-rotatably coupled.

[0014] The rotor of an electric axial flux machine can be designed, at least in part, as a laminated rotor. A laminated rotor is constructed in axial layers. The axial magnetic flux must overcome the adhesive or insulation layers between the stacked individual electrical sheets, causing shearing of the magnetic circuit (an additional air gap) and a loss of efficiency. Alternatively, the rotor of an axial flux machine can also have a rotor carrier, which is equipped with magnetic sheets and / or SMC material and with magnetic elements designed as permanent magnets.

[0015] Advantageous embodiments of the invention are specified in the dependent claims. The features listed individually in the dependent claims can be combined with one another in a technologically expedient manner and can define further embodiments of the invention. Furthermore, the features specified in the claims are further specified and explained in the description, with further preferred embodiments of the invention being presented.

[0016] According to an advantageous embodiment of the invention, it can be provided that each of the wound stator teeth is actually divided into at least two stator partial teeth, viewed in the radial direction, whereby the optimized winding cross-section of the axial flux machine is fully utilized.

[0017] According to a further preferred development of the invention, it can also be provided that the stator winding of a stator tooth is divided into at least two subgroups. A first subgroup of the stator winding encloses the radially outermost stator subtooth and each further subgroup additionally encloses the next stator subtooth arranged radially in the direction of the stator central axis X, with the last subgroup enclosing all stator subteeth. This makes it possible to achieve particularly efficient winding of the stator teeth with a large winding cross-section, particularly in the radially outer regions, without the flux-conducting elements in the radially inner regions having to be designed to be disadvantageously narrow. This makes it possible to achieve a more constant ratio of winding cross-section to flux-conducting material across the different diameters.

[0018] As an alternative to the type of winding of a stator tooth described above, it can be provided that the stator winding of a stator tooth is divided into subgroups, wherein a first subgroup encloses a stator subtooth arranged between the radially outermost stator subtooth and the radially innermost stator subtooth, and each further subgroup additionally encloses the next stator subtooth arranged radially in the direction of the stator central axis X and / or in the direction radially away from the stator central axis X. This makes it possible to reduce torque fluctuations during operation, e.g. due to pole spacing (similar to an interlacing of the magnets with respect to the winding slots). Furthermore, ohmic losses and the associated heating can be specifically concentrated in defined areas of the stator.

[0019] According to another particularly preferred embodiment of the invention, the separating grooves formed between the stator partial teeth can be circularly arc-shaped with a center in the stator central axis X, circularly arc-shaped with a center outside the stator central axis X, or rectilinear as a secant of a circle and forming a polygonal shape. This can, in particular, improve the assembly of the windings. Furthermore, unnecessary bends in the winding heads can be avoided, thereby optimizing the electrical resistance.

[0020] Furthermore, the invention can also be further developed in such a way that a detachable, one-piece pole shoe cap, extending over all stator teeth, is attached to the free axial end of individual stator teeth. The closed pole shoe cap increases the strength of the stator and achieves a more favorable magnetic flux in the air gap.

[0021] In a further development of the pole shoe cap, it can be provided that partial areas of individual stator partial teeth extending in the axial direction are formed on the pole shoe cap, wherein the partial areas of the pole shoe cap interact in a form-fitting manner with partial areas of the stator partial teeth in such a way that a form-fitting connection for torque transmission is ensured in the circumferential or tangential direction.

[0022] This ensures that the circumferential forces can be transferred from the pole piece cap to the stator in a particularly simple and robust manner.

[0023] It may also be advantageous to further develop the invention such that, viewed in the radial direction, a single or a maximum of two layers of a subgroup of the stator winding are arranged one above the other in at least one of the separating slots of a stator partial tooth. This can promote the cooling of the windings in a targeted manner.

[0024] According to a further preferred embodiment of the subject matter of the invention, it can be provided that the stator is designed to operate an electrical machine in an H-arrangement with rotor bodies arranged axially on both sides, wherein the stator body is preferably designed to be mirror-symmetrical to a plane perpendicular to the axis of rotation of the electrical machine.

[0025] Furthermore, the object underlying the invention is achieved by an electrical 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 the rotor shaft, wherein the at least one stator of the machine is designed according to the stator described above. This creates an electrical axial flux machine that, compared to axial flux machines of the same size, realizes an optimized winding cross-section of the stator teeth.

[0026] The invention and the technical environment are explained in more detail below with reference to the figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and combine them with other components and findings from the present description and / or figures. In particular, it should be noted that the figures and in particular the proportionalities shown are only schematic. The same reference symbols denote the same objects, so that explanations from other figures can be used as a supplement if necessary.

[0027] They show: Figure 1: an axial flux machine in H-arrangement with single tooth winding in schematic representation in perspective view, Figure 2 the axial flux machine according to Figure 1in a partial exploded view, Figure 3 shows a stator tooth with a stator tooth body (top) and a stator tooth winding (bottom) of a segmented stator according to the invention, in a schematic perspective view, Figure 4 shows an axial flux machine in an I-arrangement with two stators enclosing a rotor centrally between them and constructed according to the invention, in an exploded view, Figure 5 shows an axial flux machine in an I-arrangement with a stator arranged axially adjacent to a rotor and constructed according to the invention, in an exploded view, and Figure 6 shows a sectional view through an electrical machine, constructed similarly to the electrical machine in Figure 5 or Figure 1 , in schematic representation.

[0028] Figure 1shows an axial flux machine 2 in an H-arrangement with single-tooth winding in a schematic perspective view. The axial flux machine 2 shown comprises 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 stator teeth 11 directed axially outward on both sides, to 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 in order to rotatably mount the electrical axial flux machine 2 in corresponding bearing receptacles of a housing.

[0029] Figure 2 shows the axial flux machine 2 according to Figure 1in a partially exploded view. The permanently excited electric axial flux machine 2 comprises the axially centrally arranged stator 1 with a stator body 10 formed from a plurality of stator teeth 11 distributed over the circumference and stator windings 3, which are wound and formed as a single-tooth concentrated winding around each of the stator teeth 11.

[0030] Each of the wound stator teeth 11 has a total of four stator partial teeth 111, 112, 113, 114, viewed in the radial direction, 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 in axial depth. The partially exploded view clearly shows that the stator windings 3 can be wound as individual tooth windings separately from the stator tooth body 11 and later applied to the stator tooth body 11. The first and second rotor bodies 41, 42 each have an annular support plate on which a plurality of pie-shaped permanent magnets matched to the stator teeth 11 are arranged. The rotor bodies 41, 42 are fastened in the axial direction to a receiving ring mounted on the rotor shaft 4 in a rotationally fixed manner by means of a total of eight fastening screws arranged circumferentially.

[0031] Figure 3shows a stator tooth 11 with a stator tooth body (top) and a stator tooth winding (bottom) of a segmented stator 1, as shown in Figure 4is shown, in a schematic representation, in a perspective view. It can be clearly seen in this view that a stator tooth 11 has individual stator partial teeth 111, 112, 113, 114, which are each separated from one another in the radial direction by a separating groove 120 running in the circumferential direction and having an axial depth. On the bottom side, the stator partial teeth 111, 112, 113, 114 are connected to one another via a plate-like base part. The structure of the stator winding 3 is clearly visible in the lower illustration, 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 from the radially outer stator partial tooth 111, which is wound with two winding layers (in the separating slot), the next inner stator partial tooth 112 is additionally wound, so that the first stator partial tooth 111 then already has four winding layers on the head side and two winding layers on the bottom side in the separating slot 120, and the second stator partial tooth 112, which is also wound, has the two winding layers in the first separating slot 120 on the head side and two winding layers of the second subgroup 32 of the stator winding 3 on the bottom side. In this way, the other two stator partial teeth 113, 114 are gradually wound along with the other, so that in the stator winding 3 shown, exactly two winding layers are arranged in each separating slot 120. Thus, with this type of winding, 4 x 2 winding layers - i.e. a total of at least eight winding layers - would be wound on the head side above and in the circumferential direction on the first stator partial tooth 111.In fact, the stator tooth 11 is wound with two additional winding layers from the outside, so that there are a total of ten winding layers.

[0032] Figure 4 shows an axial flux machine 2 in an I-arrangement with two stators 1 constructed according to the invention, which enclose a rotor body 41, 42 centrally between them, in an exploded view. The centrally arranged rotor body 41, 42 has a plurality of permanent magnets distributed axially on both sides around the circumference, each of which interacts with the wound stator tooth bodies spaced apart by an air gap.

[0033] Figure 5 shows an axial flux machine 2, also in an I-arrangement, with only one stator 1 constructed according to the invention, arranged axially adjacent to a rotor, in an exploded view. The stator is constructed in the same way as described above.

[0034] Figure 6shows a sectional view through an electrical machine 2 in a schematic representation. The right-hand illustration shows the sectional plane, while the left-hand illustration shows a view from above onto the highly schematically illustrated sectional plane. The stator 1 can be clearly seen with a stator tooth 11 extending axially in the direction of the rotor body 41, 42. A partial area 21 of the stator tooth 11 is formed on a pole shoe cap 20 which is to be fastened axially to the end face of the stator tooth 11, so that the complete stator tooth 11 is only formed when the pole shoe cap 20 is installed. The pole shoe cap 20 is separable and advantageously in one piece, extending over all the stator partial teeth 111, 112, 113, 114, and is fastened to the end face of the free axial end of individual stator partial teeth 111, 112, 113, 114.The partial areas 21 of the stator teeth 11 attached to the pole piece cap 20 interact in a form-fitting manner with partial areas of the stator partial teeth 111, 112, 113, 114, such that a form-fitting connection for torque transmission is ensured in the circumferential or tangential direction.

[0035] 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 named 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. List of reference symbols

[0036] 1 Stator 2 Axial flux machine 3 Stator winding 4 Rotor shaft 10 Stator body 11 Stator tooth 111 Stator partial tooth 112 Stator partial tooth 113 Stator partial tooth 114 Stator partial tooth 20 Pole shoe cap 21 Partial area of ​​stator partial tooth (formed on pole shoe cap) 31 Partial stator winding group 32 Partial stator winding group 33 Partial stator winding group 34 Partial stator winding group 41 Rotor body 42 Rotor body

Claims

1. A stator (1) for an electric axial flux machine (2), in particular a stator (1) for an axial flux machine (2) designed as a drive machine for an electrically driven motor vehicle, wherein the stator (1) has: a stator body (10) with a plurality of stator teeth (11) arranged distributed over the circumference, wherein at least one of the stator teeth (11) is divided into at least two partial stator teeth (111, 112, 113, 114) as viewed in the radial direction, and stator windings (3) which are arranged around the stator teeth (11), characterized in that the at least two partial stator teeth (111; 112) are wound with a different number of windings of the same phase of the stator winding (3).

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

3. The stator (1) according to 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): a first subgroup (31) encloses the radially outermost partial stator tooth (111), each further subgroup (32, 33, 34) additionally encloses the next partial stator tooth (112, 113, 114) arranged radially in the direction of the central stator axis (X), and the last subgroup (34) encloses all partial stator teeth (111, 112, 113, 114).

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

5. The stator (1) according to one of claims 1 to 4, characterized in that the separating grooves (120) formed between the partial stator teeth (111, 112, 113, 114) are in the shape of a circular arc with a centre in the central stator axis (X) or are in the shape of an arc with a centre outside the central stator axis (X) or are rectilinear forming a polygonal shape.

6. The stator (1) according to one of claims 1 to 5, characterized in that a pole piece cap (20) is separably fastened in one piece, extending over all partial stator teeth (111, 112, 113, 114), on the end face at the free axial end of individual partial stator teeth (111, 112, 113, 114).

7. The stator (1) according to claim 6, characterized in that subregions (21) of individual partial stator teeth (111, 112, 113, 114) are formed on the pole piece cap (20).

8. The stator (1) according to one of claims 1 to 7, characterized in that, in at least one of the separating grooves (120) of a partial stator tooth (111, 112, 113, 114) as viewed in the radial direction, one single or at most two layers of a subgroup of the stator winding () are arranged.

9. The stator (1) according to one of claims 1 to 8, characterized in that the stator (1) is designed to operate an electric machine (2) in an H-arrangement with rotor bodies (41, 42) arranged axially on both sides, and the stator body (10) is designed mirror-symmetric to a plane perpendicular to the axis of rotation of the electric machine (2).

10. An electric axial flux machine (2), having at least one stator (1) according to one of claims 1 to 9 and a first rotor body (41; 42) arranged on a rotor shaft (4) or a first rotor body (41) and a second rotor body (42).