AT522710A1 - Stator for an axial flux machine - Google Patents

Abstract

The invention relates to a stator (3) for an axial flow machine, comprising a plurality of stator teeth (6) which have two end sections opposite in an axial direction (7) and a tooth core (10) between the end sections, the stator teeth (10) having one Have SMC material. The tooth cores (10) each have - viewed in plan view - a core filling (13) and a core shell (14), the core fillings (13) being formed from a soft magnetic material and furthermore either the core shells (14) or the core shells and at least a part of at least one of the end sections of the stator teeth (6) are formed from the different SMC material.

Description

sen, the stator teeth having an SMC material.

The invention further relates to an axial flow machine comprising at least one

Stator and at least one rotor.

Electrical assemblies with a disc-shaped rotor and a paralle! | Stator arranged for this purpose are known from the prior art and are used, for example, in axial flux machines. The rotor usually has a plurality of permanent magnets which, separated by an air gap, rotate past opposing electromagnetically excitable poles of the stator. The electromagnetically excitable poles are designed as stator teeth made of a soft magnetic material, as described, for example, in DE 10 2016 207 943 A1, around the tooth core of which an electrically conductive winding generates a magnetic field when energized. A torque is applied to the rotor by energizing the stator teeth or their windings, which are arranged uniformly and concentrically in the circumferential direction of the stator, depending on the rotor position. Depending on the application, very high performance and / or

Torque densities are required.

The object of the present invention was to provide a stator for an axial flow machine

provide machine with a high specific torque.

The object of the invention is achieved with the aforementioned stator

in that the tooth cores - viewed in plan view - each have a core filling

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Stator teeth are formed from the different SMC material.

Furthermore, the object of the invention is achieved in the axial flux machine mentioned at the outset in that the stator or stators are designed according to the invention.

forms is or are.

The advantage here is that due to the hybrid design of the teeth, the magnetic flux density through the tooth (neck) can be increased, whereby the efficiency and the torque or the torque density of the axial flux machine can be increased depending on the design priority. Due to the combination of materials, the three-dimensional magnetic flux guidance achieved by the SMC material can be maintained even if the magnet utilization is significantly higher due to the increased flux density in the body of the teeth. Thus, an axial flux machine can be made available which, compared to a prior art axial flux machine of the same size, provides more power with the same installation space or requires less installation space with the same output, whereby the weight of the axial flux machine can be reduced. In addition, it also means that cheaper materials are used

for the filling, compared to the more expensive SMC materials.

According to one embodiment, the core fillings are preferably each formed from a laminated core, which results in a higher 2D flux density in the core.

can be enough.

According to one embodiment of the stator, it can be provided that the laminated cores are formed from metal sheets of different widths. This makes it easier to “fill” the teeth with the laminated core by machine. In addition, the stamping waste for the production of the laminated cores can be significantly reduced.

be dued.

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can be achieved by up to 40% compared to pure SMC teeth.

A further variant of the stator provides that the laminated cores are each made from a rolled sheet, which also reduces punching waste.

can be adorned.

In a further embodiment variant of the stator it can be provided that the laminated core or the laminated cores has / have sheet metal lamellas which are connected to one another. By connecting the sheet metal lamellas, the ma

fast handling of the laminated stacks can be improved.

The sheet metal lamellas are preferably connected to one another without short-circuits, for example glued to one another or baked with a baking varnish. But it is also possible for the sheet metal lamellas to be welded to one another, in particular

are spot welded, caulked or jammed.

According to another variant of the stator, it can also be provided that electrical insulation is arranged between the sheet metal lamellas,

whereby eddy currents can be better prevented.

According to another embodiment of the stator it can be provided

that the core shells each exclusively form a shell for the core fillings. In other words, continuous recesses for receiving the core filling are provided from one end area to the second end area. With this design variant, a simple and quick filling

development of the tooth envelopes with the dental fillings.

However, according to an embodiment variant, it is also possible for the core sheaths to each form a jacket and a cover for the core fillings. The advantages of this variant are particularly evident when the dental fillings are produced before the tooth sheaths are arranged.

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be that an end area is formed by a rolled sheet metal and in particular forms a return element of the stator. Due to the rolled stator back yoke, the punching waste can also be reduced compared to the "layered" back yoke.

be dued.

According to another embodiment of the stator, in order to increase the efficiency of the stator, provision can be made for the return element to be formed from a rolled, grain-oriented electrical sheet, the crystallographic

Preferred direction is formed in the tangential direction.

However, it can also be provided that the return element and the core fillings are formed in one piece with one another, so that better contact between the return element and tooth fillings can be achieved. In addition

the number of individual parts for assembling the stator can be reduced.

According to a preferred embodiment of the axial flux machine, this has two stators to increase the power density, with between the

a rotor is arranged on both stators in the axial direction.

For a better understanding of the invention, it will be based on the following

Figures explained in more detail.

They each show in a simplified, schematic representation:

1 shows an axial flow machine;

2 shows a stator in an oblique view from the air gap and with some magnets;

3 shows the arrangement according to FIG. 2 in an oblique view of the return element;

4 shows a variant embodiment of a stator tooth in a view from the air gap;

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6 shows another embodiment variant of a stator tooth in a view from above;

7 shows the stator tooth according to FIG. 6 in a side view;

8 shows a rolled yoke element in an oblique view;

9 shows a section of the return element according to FIG. 8 with a

put stator tooth;

10 shows a detail from another embodiment of a rolled stator with stator teeth partially cut and in oblique

view; 11 shows a variant embodiment of an axial flow machine.

By way of introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference symbols or the same component designations, whereby the disclosures contained in the entire description can be transferred accordingly to the same parts with the same reference symbols or the same component names. The position details chosen in the description, such as above, below, to the side, etc., also relate to the figure immediately described and shown and are these position-

in the event of a change in position, information must be transferred to the new position accordingly.

1 shows an axial flux machine 1 comprising an optional housing 2, a stator 3 and at least one rotor 4. In the embodiment variant shown, the axial flux machine 1 comprises two rotors 4, between which the stator 3 is arranged. On the rotor 4 or the rotors 4 are magnets 5, for example

wise permanent magnets, arranged.

A plurality of stators 3 can also be arranged. In this case, all stators 3 are preferably designed the same, so that the following statements also

can be applied to the stators 3 which may still be present.

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or is at least partially inserted into the return element 12.

The tooth core 10 therefore extends exclusively over the area of the coil winding 11. The areas of FIG

Stator teeth 6 are to be assigned to either the tooth tip 8 or the tooth root 9.

It should be mentioned, however, that, as will be described later, the tooth core 10 can extend at least partially into at least one of the two end regions, that is to say, for example, into the tooth tip 8, and can form at least part of it. Thus, a material from which the tooth core 10 is made or which it comprises can also be present in at least one of the end regions

be.

The tooth root 9 and / or the tooth tip 8 can be formed in one piece with the tooth core 10. However, there is also the possibility that the tooth root 9 and / or the tooth head 8 with the tooth core 10 via an adhesive connection or

Like. Is / are connected.

For better utilization of the machine space, the tooth root 9 and / or the tooth tip 8 can have a larger cross-sectional area than the tooth core 10

have so that they protrude (fully) over this. The tooth root 9 can also form the return element 12

At least one is not between the coil winding 11 and the tooth core 10

further illustrated electrical insulation arranged.

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desired performance features.

The stator teeth 6 are evenly distributed over the circumference of the stator 3.

arranges.

The stator teeth 6 as a whole and also the tooth cores 10, viewed in the direction of the axial direction 7, have an at least approximately trapezoidal cross-sectional

area on.

In FIGS. 2 and 3, the magnets 5 of the rotor 4 (FIG. 1) are also shown for the sake of completeness. Some of the magnets 5 have been removed in order to

To enable sere insight into the stator teeth 6.

The in particular ring-shaped return element 12 of the stator 3 can consist of

a material customary for this purpose.

The tooth cores 10, on the other hand, are designed as hybrid elements and have a core filling 13 and a core sheath 14, which can be seen better from FIG

together with FIG. 4 shows a first variant embodiment of a stator tooth 6.

It should be pointed out at this point that only one stator tooth 6 is described below. These statements can also be transferred to the further stator teeth 6 of the rotor 4, since preferably all of them

Stator teeth 6 are formed the same.

In the embodiment variant shown, the core sheath 14 is formed in one piece with the tooth head 8. In addition, the tooth root 9 is partially formed by the return element 12. For this purpose, the return element 12 has a recess in which the stator tooth 6 is received in a form-fitting manner, as can be seen in particular from the cross-sectional view in FIG. 5. The one not about that

Tooth core 10 protruding part of the tooth root 9 is thereby through the core shell

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the tooth base 9 can have the shape of the tooth tip 8.

The core sheath 14 (like the tooth head 8 in this embodiment variant) consists of an SMC material (Soft Magnetic Composite). It is preferably manufactured using powder metallurgy and enables low-loss, three-dimensional magnetic flux guidance. Since such methods are known per se, they are not necessary

further information on this.

SMC materials have been known for a long time. It is a powder made of soft magnetic material, the surface of which is covered with an electrically insulating layer. These powders are consolidated into soft magnetic components by pressing. The SMC powder has particles which comprise a core which is surrounded by an insulating layer or a plurality of insulating layers, or consists of the core and the at least one insulating layer. If necessary, a binder layer can also be applied on the outside of the insulating layer, with which the

individual particles can be connected to each other.

The core of the SMC powder particles can contain or consist of pure iron. However, other magnetizable materials or alloys can also be used as the core, such as iron alloys, which are usually used for manufacture

used by electrical steel sheets.

This core is completely surrounded by the at least one insulating layer. The at least one insulating layer can be of an organic nature, e.g. a silicone varnish, or an organometallic or inorganic nature, e.g. an oxide layer, a silicate layer, a phosphate layer. In the case of several insulating layers, these can also consist of different materials, for example selected from

the mentioned materials.

The insulating layer or the insulating layers can have an average layer thickness (arithmetic mean of at least ten individual values) between 0.01 μm and

800 µm.

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In principle, this structure of SMC powders is also from the state of the art

nik, so that further details are not necessary.

The core filling 13 of the stator teeth 6, on the other hand, is formed from an iron-based material that is different from the SMC material or comprises this. For example, an electrical sheet can be used, as is known for electrical machines and magnetic circuits with changing magnetic fields.

is set.

According to a variant of the embodiment of the stator tooth 6 just described, only one of the end sections, in particular the tooth head 8, can also consist of the SMC material. In this case, the tooth envelope 14

formed from the material of the core filling 13 or consists of this.

The core filling 13 preferably fills the volume surrounded by the tooth shell 14

90% to 100%, especially 100%.

According to a preferred embodiment of the stator 3, the core filling 13 is formed by a laminated core made of several metal sheets 15. Known electrical steel sheets can be used for this purpose, for example non-oriented magnetic steel sheets. According to a further embodiment variant, grain-oriented magnetic (steel) sheets can be used to increase performance. Grain-oriented sheets 15 per se are known from the prior art, so reference is made to them. When used for the core fillings 13 of the stator teeth 6, the crystallographic orientation of these sheets is in the axial direction

educated.

The sheets 15 preferably have a sheet thickness selected from a range from 0.05 mm to 0.5 mm. A width and a length of the sheets 15 is usual

usually significantly larger than the sheet thickness.

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The metal sheets 15 are arranged to run perpendicular to the end regions of the stator tooth 6. They are therefore arranged upright in the core shell 14, as can be seen from FIGS. 4 and 5. Furthermore, the surface of each metal sheet 15 defined by the length and width is preferably arranged vertically in a radial direction 16 through the stator tooth 6 in the stator tooth 6 or in the stator 3, as shown in FIG. The lateral end faces of the metal sheets 15 therefore point approximately in the circumferential direction 17 of the stator 3. By “approximately” it is meant that the annular design of the stator 3 must be taken into account

is.

According to one embodiment variant, it can be provided that the laminated core is made from a wound sheet metal. To do this, a sheet metal is wound onto a mandrel. The cavity surrounded by the core envelope 14 can in this case also have a trapezoidal cross section (viewed in the direction of the axial direction 7).

It should be mentioned at this point that the terms “wound” and “rolled” are used synonymously with regard to a sheet-metal package made from a metal strip

will.

The winding of the metal strip creates a laminated core consisting of sheet metal lamellas arranged one above the other in the radial direction (immediately after winding, the sheet metal lamellae are still connected due to the band winding). For better handling of the wound laminated core, in particular when the core fillings 13 are produced therefrom, the sheet metal lamellas can be connected to one another. The connection can be made, for example, by means of a punch package, caulking the sheet metal lamellae with one another, generally by clamping the sheet metal lamellae together, etc. In addition to this type of connection, the sheet-metal lamellae can also be connected exclusively due to the friction between the sheet-metal lamellae. For this purpose, the metal tape can be wound under tension. In addition to the form-fitting or non-positive connection types, the sheet metal lamellas can also be materially connected

be, for example by spot welding, gluing, baking, etc .. For baking

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a so-called baking varnish is applied to at least one side of the metal strip and then the connection is made at an elevated temperature via the varnish. The paint can simultaneously form electrical insulation between the sheet metal lamellas. In general, however, it is also possible to arrange electrical insulation between the sheet metal lamellas, for example in strips

form, whereby the strip can be wrapped with the metal tape.

The explanations for the connection of the sheet metal lamellas with one another and for insulation against one another can generally be

so-called laminated cores are used.

There is the possibility that the laminated core is formed from sheets of different widths, that is to say is designed as a “stepped” sheet stack when viewed from above. For this purpose, the individual metal sheets 15 can be punched out of a larger sheet metal in the appropriate shape or cut from a sheet metal strip with the correct width. In this case, the side walls of the core shell 14 can be designed with steps on the cavity receiving the laminated core, as can be seen from FIGS. 2 and 3. The individual metal sheets 15 can be designed as right-angled strips, which are held loosely in a magazine and inserted into the cavity of the core casing 14 during the assembly process.

can be added.

In FIGS. 6 to 10 further and possibly independent design variants of the rotor 2 or of the stator tooth 6 are shown, the same reference numerals or component designations being used for the same parts as in the previous FIGS. 1 to 5. To avoid unnecessary repetitions, please refer to the detailed description of Figures 1 to 5.

pointed or referred to.

In the embodiment variant of the stator 3 and the stator tooth 6 shown in FIGS. 4 and 5, the core casing 14 exclusively forms a jacket for the core filling 13. In other words, the cavity is for receiving the

Core filling 14 open at the top and bottom, i.e. the recess for receiving

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of the core filling 13 is designed as a breakthrough through the stator tooth 6. The

Core cover 14 forms a sleeve for core filling 13.

In contrast to this, FIGS. 6 and 7 show a variant embodiment of a stator tooth 6 of the stator 3 (FIGS. 2 and 3), in which the core casing 14 has a blind hole for receiving the core filling 13. In this embodiment variant, the core casing 14 not only forms the jacket for the core filling 13, but also a cover. The cover is formed in one piece with the jacket. The stator tooth 6 is thus completely closed in one end area with the SMC material.

For the sake of completeness, it should be mentioned that the SMC material is used as a flow collector

serves.

In general, it can apply to all embodiment variants of the invention that a wall thickness 18 of the core sheath 14 is at least 2 mm. This wall thickness

but can also be larger, depending on the variant and machine size.

A wall thickness 19 of the cover described can be between 2 mm and 10

mm.

The (ring-shaped) return element 12 (FIGS. 2 and 3) can be designed as a compact plate. According to a variant embodiment of the stator 3, which is shown in FIG. 8, it can be provided that the return element 12 is designed as a rolled sheet metal, i.e. as a rolled sheet metal strip 20. According to a further embodiment variant, this return element 12 can also form an end region of the stator tooth 6. The return element 12 can consist of just a single

gene sheet metal strips 20 be made.

The sheet thickness of the rolled sheet metal strip 20 can be between 0.05 mm and 0.5

mm.

With this variant, the punching waste for the production of the back

Closing element 12 can be significantly reduced or almost eliminated. In addition

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An anisotropic material can also be used for the return element 12

will. The use of an isotropic material is also possible.

According to one embodiment of the stator 3, it can be provided that the return element 12 is formed from a rolled, grain-oriented electrical sheet, the preferred crystallographic direction in the tangential direction.

device is formed.

As indicated in FIG. 8 and shown in FIG. 9, the stator tooth 6 can simply be placed on the return element 12 (or in a corresponding groove in it

inserted) and connected to it, e.g. glued.

Although FIG. 9 shows the variant of the stator tooth 6 according to FIGS. 4 and 5 with the continuous recess for the metal sheets 15, the stator tooth 6 can also be designed differently, in particular with the blind hole.

hen, as shown in FIGS. 6 and 7 for this embodiment variant.

It is possible that in the variant of the stator 3 according to FIG. 9, an anisotropic material is also used both for the metal sheets 15 and for the return element 12, i.e. in particular the sheet metal strip 20. The usage

an isotropic material is also possible.

According to an embodiment variant of this, which is shown in FIG. 10, there is the possibility that the return element 12 and the core filling 13 are formed in one piece with one another. The return element 12 is here also made from a (single) rolled sheet metal strip 20. In this case, for the return element 20 and the sheets 15 of the core filling 13, in particular one

isotropic material used.

Although FIG. 10 shows the variant of the stator tooth 6 according to FIGS. 4 and 5 with the continuous recess for the metal sheets 15, the stator tooth 6 can also be designed differently, in particular with the blind hole.

hen, as shown in FIGS. 6 and 7 for this embodiment variant.

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In Fig. 11, a further embodiment of the axial flow machine 1 is shown. In contrast to the embodiment variant of the axial flow machine 1 according to FIG. 1, it does not have two rotors 4, but only one rotor 4. The rotor 4 is - viewed in the axial direction - arranged between two stators 4 which are designed according to the invention. The rotor is equipped with several magnets 5 (permanent magnets) on both sides. The two stators 4 are arranged in such a way that the return element 12 is in each case on the

th side of the stator 3, ie outside, are arranged.

The stator 3 according to the invention can, for example, be used in a traction machine

be used for motor vehicles or aircraft.

The exemplary embodiments show possible design variants of the stator 3 or the stator tooth 6, with combinations of the individual design variants

riants are possible with each other.

For the sake of order, it should finally be noted that for a better understanding of the structure of the axial flux machine 1, the stator 3 or the stator

tooth 6 these are not necessarily shown to scale.

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15th

List of reference symbols

Axial flux machine housing

stator

rotor

magnet

Stator tooth axial direction tooth tip

Tooth root

Tooth core coil winding return element core filling core envelope

sheet

Direction circumferential direction wall thickness wall thickness

Sheet metal strips

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Claims (15)

Claims 1. A stator (3) for an axial flux machine, comprising a plurality of stator teeth (6) which have two end sections lying opposite one another in an axial direction (7) and a tooth core (10) between the end sections, the stator teeth (10) having an SMC Have material, characterized in that the tooth cores (10) - viewed in plan view - each have a core filling (13) and a core shell (14), the core fillings (13) being formed from a soft magnetic material and furthermore either the core shells (14) or the core shells and at least a part of at least one of the end sections of the stator teeth (6) from the different SMC work fabric are formed. 2. stator (3) according to claim 1, characterized in that the core fillings (13) are each formed by a laminated core. 3. stator (3) according to claim 2, characterized in that the sheet metal packages are formed from metal sheets (15) of different widths. 4. stator (3) according to claim 2 or 3, characterized in that the laminated cores are formed from grain-oriented electrical steel sheets, the crystallo- graphic preferred direction is formed in the axial direction. 5. stator (3) according to one of claims 2 to 4, characterized in net that the laminated cores are each made from a rolled sheet. 6. stator (3) according to one of claims 2 to 5, characterized in that the laminated core or the laminated cores interconnected sheet metal has / have mellen. N2018 / 33000-AT-00 7. stator (3) according to claim 6, characterized in that the sheet-metal lamellae are welded or glued in places or verba- stuck or caulked or jammed. 8. stator (3) according to claim 7, characterized in that between the sheet metal lamellas an electrical insulation is arranged. 9. stator (3) according to one of claims 1 to 8, characterized in that the core sheaths (14) each have only one jacket for the core filling lungs (13). 10. stator (3) according to any one of claims 1 to 9, characterized in that the core sheaths (14) each have a jacket and a cover for the Form core fillings (13). 11. stator (3) according to one of claims 1 to 10, characterized in that an end region of the stator teeth (6) is formed by a rolled sheet metal and in particular forms a return element (12) of the stator (3). 12. Stator (3) according to claim 11, characterized in that the return element (12) is formed from a rolled, grain-oriented electrical sheet, the crystallographic preferred direction in the tangential direction is trained. 13. Stator (3) according to claim 11, characterized in that the return element (12) and the core fillings (13) are made in one piece with one another. are formed. 14. Axial flux machine (1) comprising a stator (3) or several sta- gates (3) and at least one rotor (4), characterized in that the stator N2018 / 33000-AT-00 (3) or the stators (3) designed according to one of claims 1 to 13 is or are. 15. Axial flux machine (1) according to claim 14, characterized in that it comprises two stators (3), wherein between the two stators (3) in a rotor (4) is arranged in the axial direction. N2018 / 33000-AT-00