AXIAL FLUX MACHINE WITH RADIALLY RUNNING STATOR WITH lamination segments

Description

[0001] The invention relates to an axial flux machine, preferably for a drive train of a purely electrically or hybrid-powered motor vehicle, with an annular stator and two rotor elements mounted so as to be rotatable relative to the stator about a (common) axis of rotation, wherein a first rotor element is arranged axially (along the axis of rotation) next to a first (axial) end face of the stator and a second rotor element is arranged axially next to a second (axial) end face of the stator, and wherein the stator has a plurality of stator cores (preferably wedge-shaped in the radial direction) distributed in a circumferential direction of a circular line running around the axis of rotation.

[0002] Axial flux machines of this type are already well known in the prior art. For example, WO 2018 / 015293 A1 discloses a stator for an axial flux machine with a stator region formed from several laminations and provided with teeth.

[0003] Further prior art is known, for example, from WO 2014 / 166811 A2, which discloses a lightweight axial flux machine in which several stator teeth are connected to each other in end regions via a respective ring structure and to a housing surrounding the stator radially on the outside. Consequently, it is already known to construct stator cores using laminations arranged laterally to the stator cores in the axial direction.

[0004] An axial flow machine according to the preamble of claim 1 is known from WO 96 / 09680 A1 (corresponds to EP 0 729 663 A1).

[0005] For further prior art, reference is made to EP 1 538 727 A2.

[0006] However, a disadvantage of these prior art designs has been shown to be that the existing magnetic resistance in the required directions is often still relatively high. Eddy currents also form in the magnetic core (intensified in the peripheral areas), which are caused by the alternating currents in the windings and the magnetic fields of the rotor. Furthermore, in some cases, mechanical strength is relatively low.

[0007] It is therefore an object of the present invention to eliminate the disadvantages known from the prior art and, in particular, to provide an axial flux machine with a stator core that is as stable as possible, while at the same time reducing the magnetic resistance in the required directions and avoiding undesirable eddy currents.

[0008] This object is achieved by the measures specified in claim 1.

[0009] At least one stator core has a plurality of radially extending and plate-shaped sheet metal segments stacked one above the other in the circumferential direction, wherein the entirety of the sheet metal segments are surrounded on their two circumferential sides facing away from each other in the circumferential direction by a cover section made of a soft magnetic composite material.

[0010] This results in several advantages. The side cover sections reduce eddy currents. The central lamination segments ensure a high magnetic flux density in the axial direction due to their low magnetic resistance in the axial direction. Due to the different magnetic resistances of the lamination and the composite material in the axial direction, the cogging torques of the rotor are reduced. Furthermore, the increased magnetic resistance in the circumferential direction in the stator core reduces the asymmetric forces on the rotor due to deviations from the ideal geometry.

[0011] Further advantageous embodiments are claimed in the subclaims and explained in more detail below.

[0012] Accordingly, it is also advantageous if the at least one stator core comprises several groups of lamination segments, with the lamination segments of the different groups differing in their radial extent. This makes it easy to achieve a stepped lamination stack arrangement.

[0013] It is therefore further advantageous if the sheet metal segments are designed and arranged in such a way that a sheet metal package arrangement is produced which changes in its extension in the circumferential direction in a single-stage or multi-stage manner in the radial direction.

[0014] In this context, it has proven particularly expedient if the at least one stator core comprises, in addition to a first group of a plurality of identically configured first lamination segments extending continuously from a radial inner side (of the stator core) to a radial outer side (of the stator core), a second group of a plurality of second lamination segments, wherein the second lamination segments have a shorter radial extent than the first lamination segments and are arranged toward a first circumferential side of the first group of first lamination segments. This further reduces the magnetic resistance.

[0015] In this regard, it is also expedient if a third group of several third sheet metal segments is arranged on a second circumferential side of the entirety of first sheet metal segments facing away from the first circumferential side, wherein the third sheet metal segments have a shorter radial extent than the first sheet metal segments.

[0016] If the first sheet metal segments of at least one stator core are designed as identical parts, they can be manufactured particularly economically in series.

[0017] In this context, it is also advantageous if the second sheet metal segments and / or the third sheet metal segments are designed as identical parts.

[0018] Preferably, the plurality of stator cores are of identical design.

[0019] One of the cover sections or both cover sections have a pole shoe contour with at least one projection projecting in the circumferential direction, whereby a further optimized contour is implemented to reduce the magnetic resistance.

[0020] In this regard, it is also expedient if the at least one projection is designed as a radially extending rib.

[0021] If the cover sections taper inwards in the radial direction, the wedge shape of the stator core can be easily produced.

[0022] Furthermore, it is expedient if each stator core is provided with a stator winding, wherein this stator winding forms a plurality of axially adjacent winding loops and the respective winding loop narrows inwards in the radial direction with regard to its circumferential width.

[0023] It is expedient if the stator winding runs parallel to a (preferably flat) circumferential surface of the first cover section towards the first circumferential side and / or runs parallel to a (preferably flat) circumferential surface of the second cover section towards the second circumferential side.

[0024] It is also advantageous if the cover sections are formed on their side facing the sheet metal segments (circumferential side) complementary to a contour of a sheet metal package arrangement formed by the sheet metal segments.

[0025] In other words, the invention provides a stator for an axial flux machine with radially extending laminations (lamination segments). The laminations of the stator core extend radially. The stator core is covered circumferentially with an SMC material (SMC = "Soft Magnetic Composite").

[0026] The invention will now be explained in more detail below with reference to various figures, which also illustrate different embodiments.

[0027] They show: Fig. 1 is a perspective view of an axial flow machine according to the invention, cut in the longitudinal direction, according to a first embodiment, wherein its structure can be clearly seen, Fig. 2 is a perspective full view of one of several stator cores, as used in the axial flow machine according to Fig. 1are inserted, from its radial outer side, Fig. 3 is a view of the stator core from its front side, Fig. 4 is a perspective view of a first sheet metal segment inserted in the stator core, Fig. 5 is a perspective view of a first cover section made of a soft magnetic composite material and inserted in the stator core, Fig. 6 is a perspective view of a partial assembly formed by the stator core and a stator winding surrounding it, Fig. 7 is a perspective view of a partial assembly consisting of a stator core formed according to a second exemplary embodiment and a stator winding surrounding this stator core, Fig. 8 is a perspective view of a coil arrangement of the stator according to the second exemplary embodiment, wherein a plurality of stator cores wound with coil windings are arranged in a row in the circumferential direction, and Fig.9a front view of the entire coil arrangement according to . Fig. 8 .

[0028] The figures are merely schematic in nature and serve exclusively to facilitate understanding of the invention. The same elements are provided with the same reference numerals. Furthermore, the features of the different embodiments can, in principle, be freely combined with one another.

[0029] With Fig. 1 1 illustrates a structure of the axial flux machine 1 according to the invention according to a preferred first embodiment. The axial flux machine 1 is used in its preferred application in a motor vehicle drive. The corresponding motor vehicle is therefore implemented either as a purely electrically powered motor vehicle or as a hybrid-powered motor vehicle.

[0030] The directions used below refer to a central axis of rotation 3 of both rotor elements 4a, 4b of the axial flux machine 1. An axial direction is therefore a direction along / parallel to the axis of rotation 3, a radial direction is a direction perpendicular to the axis of rotation 3 and a circumferential direction is a direction along a circular line of constant diameter running coaxially around the axis of rotation 3.

[0031] According to the design of an axial flux machine 1, it has a substantially ring-shaped stator 2 which rotates completely in the circumferential direction ( Fig. 1 ). It can be seen that the stator 2 has a thickness (axial extent) that is less than its height (radial thickness / height of the annulus). In further embodiments, the axial extent can also be greater / longer than the radial height of the annulus of the stator 2.

[0032] In addition to the stator 2, as already mentioned, the two rotor elements 4a, 4b are part of the axial flux machine 1. A first rotor element 4a is arranged on a first (axial) end face 5a of the stator 2. A second rotor element 4b is arranged on a second (axial) end face 5b of the stator 2, axially facing away from the first end face 5a. The rotor elements 4a, 4b are each essentially identical. Both rotor elements 4a, 4b each have a disk-shaped base body 23 and a plurality of magnets 24 (permanent magnets) distributed in the circumferential direction, which magnets 24 are arranged on an axial side of the rotor elements 4a, 4b facing the stator 2. The rotor elements 4a, 4b are typically mounted so as to be rotatable about the axis of rotation 3 relative to the stator 2.

[0033] As also with Fig. 1 As shown, the stator 2 is equipped with several stator cores 6 distributed in a circumferential direction of the rotation axis 3.

[0034] The stator cores 6 are each realized as identical parts. Each stator core 6 serves to accommodate a stator winding 21, which has several winding loops 22 arranged next to one another in the axial direction ( Fig. 6 ). Stator core 6 and stator winding 21 typically form a stator coil 25 / coil arrangement. The stator coils 25 are arranged uniformly and adjacent to one another in the circumferential direction. The stator coils 25 taper in the radial direction toward their inner side. Each stator coil 25, i.e., each stator core 6 and each stator winding 21, thus has a wedge-shaped extension that reduces in the circumferential direction, viewed along its radial extension.

[0035] Taking into account the Figs. 1 to 3It can further be seen that each stator core 6 according to the invention has a plurality of first lamination segments 7 aligned / running in the radial direction of the rotation axis 3. Each first lamination segment 7 runs along the entire radial length of the stator cores 6 or directly forms the radial ends of the stator core 6. Figs. 4 and 7 A first sheet metal segment 7 is shown as an example for the other first sheet metal segments 7. The first sheet metal segment 7 is rectangular and has a greater extension in the radial direction than in the axial direction (preferably from an outer diameter of 200 mm), although this is not mandatory. Several first sheet metal segments 7 are arranged stacked one above the other in the circumferential direction to form a sheet metal package and are each insulated from one another in a typical manner by means of an intermediate insulation layer (not shown here for the sake of clarity).

[0036] The first lamination segments 7 are realized as identical parts. In this first embodiment, the first lamination segments 7 form a laminated core arrangement 12 with a constant thickness across the entire radial height of the stator core 6 (extension in the circumferential direction).

[0037] In addition to the first group of first lamination segments 7, the respective stator core 6 has two wedge-shaped cover sections 11a, 11b, each made of a soft magnetic composite material. A first cover section 11a is applied to the first circumferential side 10a of the group of first lamination segments 7, while a second cover section 11b is applied to the second circumferential side 10b of the group of first lamination segments 7.

[0038] The two cover sections 11a, 11b are shaped the same, whereby in Fig. 5the first cover section 11a is illustrated as a representative example. The first cover section 11a is accordingly formed with a flat bearing surface 17 on a side which bears against the first lamination segments 7 in the circumferential direction. On a side facing away from the lamination segments 7 of the same stator core 6 in the circumferential direction (first circumferential side 10a), the first cover section 11a forms a (first) circumferential surface 18a. The circumferential surface 18a is delimited on its axial sides by a projection 16a, 16b each forming a pole shoe contour 15. The two projections 16a, 16b protrude in the circumferential direction. Each projection 16a, 16b forms a rib running in the radial direction (over the entire radial height of the stator core 6).

[0039] As continued in Fig. 6As can be seen, the stator winding 21 extends with a first section 19 parallel and adjacent to the first circumferential surface 18a. With a second section 20, the stator winding 21 extends parallel and adjacent to the (second) circumferential surface 18b of the second cover section 11b.

[0040] With the Figs. 7 to 9a further second exemplary embodiment is shown. According to the second exemplary embodiment, there is no longer just a first group of first lamination segments 7 provided in the respective stator core 6. There is also a second group of second lamination segments 8 and a third group of third lamination segments 9. The second lamination segments 8 are arranged towards the first circumferential side 10a in direct contact with the first lamination segments 7. The third lamination segments 9 are arranged towards the second circumferential side 10b in direct contact with the first lamination segments 7. In this embodiment, the second lamination segments 8 and the third lamination segments 9 are identical / designed as identical parts.

[0041] However, the second lamination segments 8 and the third lamination segments 9 are shorter in the radial direction than the first lamination segments 7. The second lamination segments 8 and the third lamination segments 9 are essentially implemented as first lamination segments 7 halved at a radial height. Every second lamination segment 8 and every third lamination segment 9 forms the outer radial end of the stator core 6 or is open towards the radial outer side 14. The entirety of lamination segments 7, 8, 9 is therefore arranged such that it forms a laminated core arrangement 12 stepped in the radial direction. In this embodiment, the laminated core arrangement 12 is simply stepped, i.e. its thickness / extension in the circumferential direction is reduced at a radial height to form a step 26. In other embodiments, however, several steps (at different radial heights) are also present.

[0042] The respective second and third sheet metal segments 8, 9 are covered by the cover sections 11a, 11b in the circumferential direction and toward the radial inner side 13. Thus, in the second embodiment, the cover sections 11a, 11b have a counter-step 27 complementary to the step 26.

[0043] The sheet metal segments 7, 8, 9 of the different embodiments are each made of an electrical sheet.

[0044] In other words, according to the invention, it is proposed that the sheets 8, 18, 19 extend radially and are covered laterally in the circumferential direction with SMC (cover sections 11a, 11b).

[0045] Figure 2shows a single stator tooth 6 without a winding. The stator tooth 6 consists of a central region made of iron sheets 7 stacked in the circumferential direction, with the individual sheet layers 7 being electrically insulated from one another. The individual sheets 7 each extend approximately in the radial and axial directions (forming a corresponding surface that is approximately perpendicular to the circumferential direction).

[0046] In the circumferential direction, the stacked sheets 7 are enclosed or covered by a material with good magnetic conductivity but poor electrical conductivity (e.g., SMC = Soft Magnetic Composite). These material sections 11a, 11b are depicted as wedge-shaped components that rest on the sheet stack 7, 12 on both sides in the circumferential direction and are, for example, fixed to the sheets 7, 12.

[0047] Fig. 3 shows the same structure, but instead of a 3D view in a top view from the axial direction. Figure 4 shows a single lamination 7 in a 3D view together with the orientation of the laminations 7 in the stator core 6.

[0048] Figure 5 shows a side part 11a made of a material with good magnetic conductivity but poor electrical conductivity (e.g. SMC = Soft Magnetic Compound). The side parts 11a, 11b have contours 16a, 16b, 15 at their ends in the axial direction for the formation of pole pieces. Between the two contours 16a, 16b for the pole pieces is the area 18a, 18b for receiving the winding 21 for the stator tooth 6. The side parts 11a, 11b can also be composed of several individual parts (e.g. by being divided perpendicular to the axial direction so that the parts can be joined by a movement in the axial direction), although this is not shown separately here for the sake of clarity.

[0049] Figure 6shows a single stator tooth 6 supplemented by an electrical winding 21. A single-tooth winding 21 is shown here, but other winding configurations are also possible. The laminations 7 in the center of the stator tooth 6 have a constant stack height across the entire radial height of the tooth 6.

[0050] Figure 7 also shows a stator tooth 6 with single tooth winding 21. In contrast to the Figure 6 The middle lamination stack 12 has different stack heights at different radial heights (in this case, two different stack heights). With greater manufacturing complexity, more stack heights 26 are possible. The different stack heights enable a better magnetic flux in the axial direction due to the higher proportion of electrical steel in the entire tooth 6.

[0051] Figure 8shows a 3D view in which several stator teeth 6 are combined to form an overall stator 2. The individual stator teeth 6 are arranged in a ring shape in the circumferential direction around the rotation axis 3 of the rotor 4a, 4b.

[0052] Figure 9 shows the same structure of Figure 8 in the top view in the direction of the rotation axis 3. Shown here are stator teeth 6 with two different stacking heights of the laminations 7, 8, 9 at different radial heights of the stator 2. A connection of the windings 21 to different phases is not shown here.

[0053] In Figure 1 The stator 2 is supplemented with a right and a left rotor 4a, 4b. The cross-section shows the magnets 24 arranged on the surface of the magnetic return path. Mechanical support of the stator teeth 6 (e.g., by means of plastic casting), the bearings of the rotors 4a, 4b, and the output shaft are not shown. List of reference symbols

[0054] 1 Axial flux machine 2 Stator 3 Rotation axis 4 a First rotor element 4 b Second rotor element 5 a First end face 5 b Second end face 6 Stator core 7 First lamination segment 8 Second lamination segment 9 Third lamination segment 10 a First circumferential side 10 b Second circumferential side 11 a First cover section 11 b Second cover section 12 Laminated core arrangement 13 Inside 14 Outside 15 Pole shoe contour 16 a First projection 16 b Second projection 17 Support surface 18 a First circumferential surface 18 b Second circumferential surface 19 First section 20 Second section 21 Stator winding 22 Winding loop 23 Base body 24 Magnet 25 Stator coil 26 Stage 27 Counter stage

Claims

1. An axial flux machine (1) comprising: an annular stator (2) having multiple stator cores (6) arranged distributed in a circumferential direction of a circular line extending about the axis of rotation (3), wherein at least one stator core (6) has multiple sheet metal segments (7, 8, 9) stacked on top of one another in the circumferential direction, extending radially and designed in the form of plates, and two rotor elements (4a, 4b) mounted so as to be rotatable relative to the stator (2) about an axis of rotation (3), wherein a first rotor element (4a) is arranged axially next to a first end face (5a) of the stator (2) and a second rotor element (4b) is arranged axially next to a second end face (5b) of the stator (2), characterised in that each of the sheet metal segments (7, 8, 9) is surrounded on its two circumferential sides (10a, 10b) facing away from one another in the circumferential direction by a cover section (11a, 11b) made of a soft magnetic composite material, and each cover section (11a, 11b) forms a circumferential surface (18a, 18b) on a side facing away from the sheet metal segments (7, 8, 9) of the same stator core (6) in the circumferential direction, which surface is bounded on its axial sides by a respective projection (16a, 16b) that forms a pole shoe contour (15 and projects in the circumferential direction.

2. The axial flux machine (1) according to claim 1, characterised in that the at least one stator core (6) has multiple groups of sheet metal segments (7, 8, 9), and the sheet metal segments (7, 8, 9) of the different groups differ in their radial extension.

3. The axial flux machine (1) according to claim 1 or 2, characterised in that the sheet metal segments (7, 8, 9) are designed and arranged in such a way that a sheet metal stack arrangement (12) is produced which changes in its extension in the circumferential direction in a single state or multiple stages in the radial direction.

4. The axial flux machine (1) according to one of claims 1 to 3, characterised in that the at least one stator core (6) has, in addition to a first group of multiple first sheet metal segments (7) which are identical to one another and extend continuously from a radial inner side (13) to a radial outer side (14), a second group of multiple second sheet metal segments (8), and the second sheet metal segments (8) have a shorter radial extension than the first sheet metal segments (7) and are arranged towards a first circumferential side (10a) of the first group of first sheet metal segments (7).

5. The axial flux machine (1) according to claim 4, characterised in that on a second circumferential side (10b) of the entirety of first sheet metal segments (7) facing away from the first circumferential side (10a), a third group of multiple third sheet metal segments (9) is arranged in addition to the second group, and the third sheet metal segments (9) have a shorter radial extension than the first sheet metal segments (7).

6. The axial flux machine (1) according to one of claims 1 to 5, characterised in that the at least one projection (16a, 16b) is designed as a radially extending rib.

7. The axial flux machine (1) according to one of claims 1 to 6, characterised in that the cover sections (11a, 11b) taper inwards in the radial direction.

8. The axial flux machine (1) according to one of claims 1 to 7, characterised in that the cover sections (11a, 11b) are shaped on their side facing the sheet metal segments (7, 8, 9) such as to complement a contour of a sheet metal stack arrangement (12) formed by the sheet metal segments (7, 8, 9).