DE102016203372A1 - Electric machine and related manufacturing process - Google Patents

Abstract

The invention relates to an electrical machine (1), in particular for a motor vehicle (motor vehicle), comprising a stator (3) with a laminated core (4), from which winding heads (5) of an electrical winding (5) are connected to at least one axial end (6). 7), wherein at the at least one axial end (6) in each case by a housing (12) and / or a respective end shield (11) an annular receiving area (13) is provided, in which the winding heads (5) are arranged. It should be provided a winding head cooling. The invention provides that between the winding heads (5) and an inner wall (14) of the receiving area (13) at least one electrically insulating, permanently elastic material (15) is arranged, which contacts the winding heads (5) and the inner wall (14) and this thermally coupled and this has a heat transfer coefficient greater than 1 W / mK.

Description

The invention relates to an electrical machine, which may be provided in particular for a motor vehicle. In the electric machine, a stator has a laminated core from which winding heads of an electrical winding protrude at least at one axial end. These winding heads are arranged in an annular receiving area, which may be provided in a housing and / or a bearing shell of the electrical machine. The invention also includes a motor vehicle with the electric machine. Finally, the invention also includes a method for producing the electric machine.

An electric machine can be provided in a motor vehicle, for example, as an on-board generator, which can be driven by an internal combustion engine of the motor vehicle and thereby generates electrical power for the electrical system. In electrical machines, a power limiting factor is the quality of the dissipated heat dissipation. A special zone, in which the dissipation of heat loss is problematic, represent the stator winding heads. If it is possible to specifically dissipate heat from this zone to the environment, the power of the electric machine can be increased while maintaining the same volume.

For a heat dissipation from the winding heads in a housing or a bearing plate of the electric machine is known to provide means for thermal coupling of the winding heads to the machine housing or the bearing plate. This is for example from the DE 199 43 446 A1 known. It is described that the winding heads are inserted into an annular receiving area of a housing which is filled with a potting compound. The potting compound additionally serves as a mechanical attachment of the winding heads in the housing. For this purpose, the receiving area undercuts, in which the potting compound flows during casting and thus forms a positive connection with the housing after curing.

A disadvantage of providing such a curing potting compound that can form cracks in mechanically highly stressed areas during operation of the electrical machine due to vibration and different thermal expansion coefficients. As a result, the thermal conductivity and strength of the potting compound is reduced. The document therefore proposes to introduce fiber materials in the potting compound.

The invention has for its object to thermally wrap end windings of a stator of an electric machine to a housing and / or a bearing shell of the electric machine.

The object is solved by the subject matters of the independent claims. Advantageous developments of the invention will become apparent from the features of the dependent claims, the following description and the figures.

The invention provides an electric machine, in particular for a motor vehicle. In a manner known per se, the electric machine has a stator with a laminated core, from which in each case end windings of an electrical winding protrude at at least one axial end. In other words, winding heads are present on one end face or both end faces of the laminated core, which protrude freely out of the laminated core. They are thus not in contact with the material of the laminated core, ie soft iron, via which otherwise in the winding heads resulting heat loss could be dissipated. At the at least one axial end, an annular receiving area is provided in each case by a housing and / or a respective end shield, in which the winding heads are arranged. It can therefore be provided an annular groove or an annular gap in which the winding heads protrude or are inserted.

In order to be able to reliably dissipate heat loss from the end windings, at least one electrically insulating, permanently elastic material is arranged between the end windings and an inner wall of the receiving region. In other words, the permanently elastic material is together with the winding heads in the receiving area. By electrically insulating is meant in particular a resistivity greater than 10 ⁵ Ωm. The material touches the winding heads and the inner wall and couples them thermally. For this purpose, the material has a heat conduction coefficient greater than 1 W / mK. In other words, between the winding heads and the inner wall, a Wärmeleitbrücke is formed from a solid. The thermally conductive material is designed permanently elastic.

By the invention there is the advantage that the thermal conductivity of the arrangement described remains reliable even with vibrations and / or a relative movement of the winding heads with respect to the inner wall of the receiving area. The material can not break due to its permanent elasticity and thereby lose its thermal conductivity due to hairline cracks.

The invention also includes advantageous developments, the characteristics of which provide additional advantages.

As a further development, the described permanently elastic material is provided preformed by an attachable or insertable molded part. In this development, the permanently elastic material is wholly or partly provided by a designed as a molded part solid, which is attached to the winding heads or applied to the winding heads. Thus, for example, a molded part made of an elastomer can be provided.

A development for this purpose provides that the molding can be produced by means of a mass production in a few manufacturing steps of a semi-finished product. In this development, the molding is configured as a flexible strip, which has recesses in an unrolled state, which are designed such that the strip when applied to the winding heads has a closed, wrinkle-free in the circumferential direction or circumferential direction. Thus, for example, the molded part can be cut out or cut off as a strip by the meter, and then the cutouts can be punched and / or cut. If the strip then curves or bends to adapt to the shape of the winding head arrangement, then the recesses close and a closed shape, for example a pot shape or a ring, which can be applied to or attached to the winding heads results.

A particularly suitable shape of the recesses is given according to a development in which the recesses have a triangular shape or a diamond shape. This can be provided with cutting tools and / or stamping tools process reliable in a mass production process.

In addition or instead of a molded part is provided according to a development that the permanently elastic material is provided in whole or in part by a plastically deformable mass. In the receiving area for the winding heads as a thermally conductive material then a viscoelastic and / or flowable mass is provided. It is therefore not, as known in the art, a cured potting body, for example made of synthetic resin. The use of the deformable mass has the advantage that the material adapts or clings to the shape of the winding heads and / or the inner wall.

According to a development, the material is designed to be self-adhesive. This results in two advantages. On the one hand, the assembly of the electric machine is simplified, since the material adheres independently to the winding heads and / or the inner wall of the receiving area and thus does not have to be held while the winding heads are inserted into the receiving area. Another advantage arises during operation of the electrical machine, since the material does not detach from the inner wall and / or the winding heads and thereby an air gap, which would affect the heat transfer from the end windings into the inner wall, can form.

The invention is particularly advantageous in mass-produced to manufacture and thereby in the production of inexpensive as possible to design electric machines. Such a machine type is a vehicle electrical system generator for a motor vehicle. Such an electrical system generator is also referred to as an alternator. The electrical system generator can also be provided as a starter generator. Accordingly, a development provides that the electrical machine is designed as such a vehicle electrical system generator.

The invention also includes a motor vehicle having an embodiment of the electric machine according to the invention. The motor vehicle according to the invention is designed in particular as a motor vehicle, for example as a passenger car or truck or utility vehicle (commercial vehicle).

The invention also includes a method for producing an embodiment of the electric machine according to the invention. The method results in a reliable thermal coupling of winding heads of an electrical winding of a stator of the electric machine with an inner wall of a receiving area, as it may be provided in a housing and / or a bearing plate of the electrical machine. In the method, a stator with a laminated core, from which protrude at least one axial end of each winding heads of an electrical winding, and for the at least one axial end each formed in a housing and / or a respective end shield, annular receiving area for the winding heads of provided respective axial end. Based on this, the provision of an electrically insulating, permanently elastic material takes place at the winding heads and / or in the respective receiving area. Then, at the at least one axial end, the insertion of the winding heads in the receiving area, in which case the permanently elastic material is subjected to a contact pressure. As a result, therefore, the elastic material is firmly seated in the receiving area between the winding heads and the inner wall of the receiving area. It presses against both the winding heads and against the inner wall. As a result, a reliable thermal coupling of the material is achieved at these two elements.

To provide the material, provides a development of the method that the material is provided in whole or in part as a strip with recesses and the strip before the insertion of the winding heads in the receiving area previously applied to the winding heads or inserted into the receiving area, so that the Strip after insertion at least forms a voltage applied to the winding heads ring. By means of the strip so the Wärmeleitbrücke is created as a preformed part of the winding heads or inserted into the receiving area. This results in the advantage that the assembly process can be done dry, so no viscous mass is to be distributed, which could inadvertently penetrate into areas of the electric machine to be kept free.

A further development, however, provides that the material is provided in whole or in part as a paste-like mass, ie as a paste. So the material has a viscoplastic property, so it can be plastically deformed as a paste and thereby smeared by its viscosity. Since it is elastic, it represents an elastic-plastic mass.

In order to improve the heat transport even further, provides a development that the pasty mass is partially distributed in intermediate spaces between the winding heads before insertion and / or by the insertion of the winding heads in the receiving area. As a result, the thermally conductive material is also arranged between the winding heads. Thus, waste heat or heat loss can be removed from the winding heads and passed through the material to the inner wall of the receiving area also from the spaces on the thermally conductive material. The aim is a high wetting and / or a high degree of filling. The introduction of the material into the spaces between the winding heads should therefore aim for optimum wetting.

In order to avoid unwanted deliquescence or distribution of the mass, a development that sets a viscosity of the mass during insertion depends on a shear rate in the mass. In other words, the mass is a dimensionally stable paste whose viscosity decreases when shear forces act on the mass. A corresponding material having a viscosity which is dependent on the shear rate may be provided by appropriate additives known in the art.

A further embodiment provides that at least one part of the material is applied in the form of at least one blank or at least one mat in ready-to-use and / or preimpregnated or pre-soaked form (so-called prepregs) or in another beta state and by application of temperature and / or another environmental condition (eg air humidity) and / or is converted by at least one other phase-unspecific activator in the final state (eg by chemical reaction, swelling or storage).

The invention also includes developments of the method according to the invention, which have features as they have already been described in connection with the developments of the electric machine according to the invention. For this reason, the corresponding developments of the method according to the invention are not described again here.

In the following an embodiment of the invention is described. This shows:

1 a schematic representation of an embodiment of the electric machine according to the invention in longitudinal section, in which in a region between end windings and an inner wall of a receiving area at least one permanently elastic material is arranged, which touches the winding heads and the inner wall and couples them thermally,

2 a schematic representation of a stator of the electric machine of 1 in a perspective view,

3 a representation of the stator of 2 in a perspective view, showing how winding heads of the stator protrude from axial ends of a laminated core,

4 a representation of an arrangement of the winding heads in a receiving area of a housing or end shield of the electric machine of 1 .

5 a schematic representation of a strip of a permanently elastic material,

6 a schematic representation of the strip of 5 which is shaped or bent into a ring,

7 a schematic representation of a strip of an elastic material with triangular recesses,

8th a schematic representation of the strip of 7 which is formed into a double ring for covering the winding heads,

9 a schematic representation of a strip with diamond-shaped recesses,

10 a schematic representation of a strip which is bent to a triple ring or pot for covering the winding heads,

11 1 is a schematic representation of the electrical machine for illustrating an assembly step, in which the permanently elastic material is provided as a pasty mass,

12 a schematic representation of the electric machine during manufacture after performing the assembly step of 11 , and

13 a schematic representation of another assembly step of the electric machine, wherein the pasty mass is disposed between the winding heads.

The exemplary embodiment explained below is a preferred embodiment of the invention. In the exemplary embodiment, the described components of the embodiment each represent individual features of the invention that are to be considered independently of one another, which also each independently further develop the invention and thus also individually or in a different combination than the one shown as part of the invention. Furthermore, the described embodiment can also be supplemented by further features of the invention already described.

In the figures, functionally identical elements are each provided with the same reference numerals.

1 shows an electric machine 1 , which may be, for example, a generator or a starter generator for a motor vehicle. The electric machine 1 can thus be provided in a motor vehicle.

An axis of rotation 2 represents an axis of symmetry of only half shown electrical machine 1 dar. The orientation of the axis of rotation 2 shows the course of an axial direction A. Shown are a stator 3 with a laminated core 4 and winding heads 5 at a respective end face or at a respective axial end 6 of the laminated core 4 stand out from this. The winding heads 5 are part of an electrical winding 7 of the stator 3 ,

In the stator 3 is a rotor 8th arranged in the stator 3 over a wave 9 by means of bearings 10 around the axis of rotation 2 can be rotatably mounted. The rolling bearings 10 can in camp shields 11 be held, which may each be provided as mutually different components or integrally in a housing 12 can be trained. Each end shield 11 can in the field of windings 5 each a receiving area 13 in which the winding heads 5 can be arranged. This allows the windings 5 from an inner wall 14 of the recording area 13 be surrounded. A material of the inner wall 14 , in particular a material of the end shield 11 in the recording area 13 is thermally conductive, for example, by being made of a metal.

About the end shield 11 or in general the housing 12 In the electric machine cooling of the winding heads 5 reached. These are the winding heads 5 with the inner wall 14 the reception areas 13 thermally by an electrically insulating, permanently elastic material 15 coupled. The permanently elastic material 15 touches both the inner walls 14 as well as the winding heads 5 and is thermally conductive so that it has a heat conduction coefficient greater than 1 W / mK. From the windings 5 about the material 15 in the inner walls 14 guided heat can then, for example, on an outside 16 the bearing shields 11 or the housing 12 in an environment 17 the electric machine 1 For example, in the air, passively discharged or actively discharged via a cooling circuit.

2 shows in schematic form the stator 3 in isolation. While the electrical winding 7 inside the laminated core 4 (please refer 1 ) over the laminated core 4 can be cooled, the winding heads protrude 5 from the end faces or axial ends 6 and are thus per se with no thermally sufficiently conductive material in contact.

3 shows the winding heads 5 in detail. The winding heads 5 For example, each may be formed by two rings or layers 18 . 19 each of a plurality of electrically conductive rods 20 . 21 are formed and two bars each 20 . 21 every layer 18 . 19 electrically connected to each other, for example, are welded. This results in a known from the prior art two-layer winding. In 3 For reasons of clarity, in each case only two of the bars are provided with a reference numeral. Each of the bars 20 . 21 may be formed, for example, of copper or aluminum. The winding type shown here is only exemplary in order to explain the operation of the invention. The electric machine 1 may also be based on another type of winding, eg a multi-strand or a round wire winding.

Since everyone is from a staff 20 and a staff 21 formed winding head is arranged at a distance from the other winding heads, is a thermal connection of the winding heads 5 to the inner wall 14 of the recording area 13 to the effect to design that a touch of the material 15 with each of the winding heads 5 is ensured.

4 shows a section IV from the representation of the electric machine 1 in 1 , Shown is how through the material 15 in the recording area 13 a radially outer outer ring 22 and an axial frontal or frontal on the end windings 5 arranged axial front ring 23 and optionally a radially inward on the end windings 5 adjoining inner ring 24 can be formed.

The material 15 is permanently elastic and can be provided, for example, by a molded part, which is formed by a solid.

5 shows how the molded part of a strip 25 can be provided. The strip may be formed, for example, from a polymer or a natural material, eg rubber. The strip may be solid or provided as a fabric or felt or sponge. The strip can be soaked.

6 shows how out of the strip 25 by applying the same to the winding heads 5 the outer ring 22 or the inner ring 24 can be formed. It may also be that the strip 25 in the recording area 13 is inserted and thereby the shape of in 6 illustrated ring assumes. The material 15 is preferably self-adhesive, so that the ring shape by adhesion to the winding heads 5 or the inner wall 14 preserved.

In 7 is a strip 25 with triangular cutouts 26 shown. The recesses 26 can be provided for example by cutting and / or punching. From the recesses 26 For the sake of clarity, only a few are provided with a reference numeral.

8th shows how out of the strip 25 according to 7 by applying the same to the winding heads 5 or by placing it in the receiving area 13 in one step the outer ring 22 and the front ring 23 can be formed. The front ring 23 is by providing the recesses 26 without folds, that is, there are no upheavals of the material 25 by bending the strip 25 to the in 8th shown front ring 23 , The thus formed front ring 23 So represents a closed in the direction of rotation, wrinkle-free form.

9 illustrated as a strip 25 diamond-shaped recesses 27 can be provided. From the recesses 27 are in 9 for clarity, only a few provided with a reference numeral.

10 shows how a strip 25 by applying to the windings 5 or by placing it in the receiving area 13 in one step the outer ring 22 , the front ring 23 and the inner ring 24 can be formed. As a result, therefore, a pot shape or a triple ring is formed. The resulting front ring 23 and inner ring 24 represent a closed in the direction of rotation, wrinkle-free form. The pot shape can on the winding heads 5 be plugged in or in the receiving area 13 be inserted.

11 illustrates a manufacturing process in which instead of a solid such as the strip 25 a paste or viscous or pasty mass 28 as a material 15 is used. This can be in the reception area 13 be provided and then the windings 5 of the stator 3 by moving along a mounting direction 29 in the recording area 13 be introduced. The mounting direction 29 corresponds to the axial direction A.

12 shows the state after completion of the assembly step of 11 , The pasty mass 28 can by applying the material 25 with the contact pressure during insertion of the winding heads 5 in the recording area 13 between the winding heads 5 and the inner wall 14 be distributed, causing another outer ring 22 , a front ring 23 and an inner ring 24 from the pasty mass 28 can form.

13 illustrated as before the assembly described in accordance with 11 An additional thermal conductivity improvement can be achieved by placing in interstices 30 between the individual winding heads 5 that is, between the pairs of electrically connected rods 20 . 21 the pasty mass 28 is arranged. This is also a heat dissipation from the interstices 30 about the material 15 in the form of the pasty mass 28 allows.

After assembly, the pasty mass can 28 cure so that they become the permanently elastic material 15 becomes.

The electric machine 1 is thus designed so that, on the one hand, a good thermal connection of the winding heads 5 to the machine housing 12 is realized, the risk of partial discharges on the winding heads to the inner walls 14 limited and a simple and safe installation is guaranteed. This is achieved by the use of an elastic, electrically insulating material 15 ,

As a particularly suitable material 15 have proven to be such materials that are available as so-called "gap filler". they allow the thermal contact between the usually liquid-cooled housing 12 or end shield 11 and the winding heads 5 of stator laminated core 4 , The housing 12 can be used as an efficient heat sink or heat sink, if it has such a material 15 with the winding heads 5 of the stator 3 is coupled. Gap fillers provide efficient heat transfer over large component distances - even and especially on uneven surfaces that can not withstand high contact pressures. During assembly, gap fillers can compensate for larger component tolerances, unevenness and different gap dimensions and can be repositioned several times. Gap-Filler are suitable for an operating temperature range of -55 ° C to +200 ° C. Due to their elasticity they themselves act as spring elements and generate the contact pressure.

Because of the thermal conductivity, there is also the advantage that due to this passive heat dissipation at low temperature differences correspondingly high power densities and a long service life due to lower operating temperatures of the electric machine 1 be enabled. In addition, this type of heat dissipation is inexpensive because it is passive, ie no air cooling for the windings 5 required, and because it is also maintenance-free.

In addition, since the thermal contact element of a gap filler is extremely soft and conformable and that between the adjacent nose-like loop loops of the pair of rods 21 . 21 The space formed by the respective winding head 30 fills, preferably as far as possible, a correspondingly good heat transfer between the winding loops of the winding head and the thermal contact element is to achieve.

Since a heat contact element made of a gap filler has a high dielectric strength and is electrically insulating, unwanted electrical flashovers or partial discharges are present at the end windings 5 excluded. Their compressibility and excellent form fit completely and permanently fill in the gaps. As elastic materials, gap fillers themselves exert pressure on the interfaces. This optimizes the thermal connection for gap dimensions in the millimeter range and at low pressure and avoids air pockets. The pressure depends on the specific elastic-plastic behavior of the material.

By self-adhesion, they are suitable for easy pre-assembly.

a.) Advantages of the concept:

• A homogeneous connection of the winding head to the heat sink by the compensation of larger unevenness,
• A good thermal conductivity to the heat sink,
• - high dielectric strength (25000 V),
• - continuous operating temperature range (-55 ° C to + 200 ° C),
• - Ability to shorten the winding head mounting space to the volume of the air gap to the housing, since the windings 5 closer to the inner wall 14 can be arranged as in the case of an air gap,
• - Increased protection of the winding heads 5 at shocks and vibrations

b.) Properties of the material 15 :

• - soft (elastic) and conformable,
• - Thermal conductivities even up to 14 W / mk possible,
• - further thickness range from 0.5 mm to 10 mm,
• - effect at very low or zero pressure,
• - vibration damping,
• - Easy pre-assembly due to self-adhesion
• - Flame retardant
• - also silicone free

c.) Possible versions:

• - Mats
• - Loose moldings and dosable

The thermo-technical contacting of the stator winding heads to be cooled 5 with the inner wall 14 or the production of the heat transfer between the winding head and the housing, can take place in different ways:

1. by molded parts (Fig. 5 to Fig. 10)

With Gap-Filler moldings you fill after inserting the blank or strip 25 in the case 12 and during assembly of the stator 3 in the case 12 , the air gaps thermally conductive but electrically insulating between the heat components and the heat sink or housing 12 ( 5 to 10 ). Various Shore hardnesses and thicknesses allow the optimal solution. Gap-Filler achieves an almost stress-free, thermally conductive but electrically insulating connection between the warm components and the heat sink or the housing 12 ,

The Gap-Filler is a metered and efficient heat conducting material with a high thermal conductivity. The filler offers one Processing time of up to four hours. When dosing and assembly thus results in a much higher flexibility.

2. metering liquid (FIGS. 11 to 13)

A gap filler as a liquid 2-component material is suitable for filling in complicated designs, remains in place after application and retains its shape ( 11 to 13 ). It offers low natural adhesion and is suitable for applications that are joined during assembly. The curing time is 24 hours at room temperature or 30 minutes at 100 ° C. In contrast to preformed gap fillers, liquid-dispensable materials allow for any thickness and thus eliminate the need for special pad thickness or punched shapes in individual applications.

Liquid dispensable 2-component materials have good heat transfer properties. They are ideal for uneven topographies. The application of fast-curing gap-fillers (Cure-in-Place) is becoming the key technology in the use of thermal management materials in the field of electronic assemblies.

Overall, the example shows how can be provided by the invention, an electric machine with winding head cooling.

LIST OF REFERENCE NUMBERS

1

Electric machine

2

axis of rotation

3

stator

4

laminated core

5

winding heads

6

Axial end

7

Electric winding

8th

rotor

9

wave

10

camp

11

end shield

12

casing

13

reception area

14

inner wall

15

Elastic material

16

outer wall

17

Surroundings

18

Layer of a two-layer winding

19

Layer of a two-layer winding

20

Rod

21

Rod

22

outer ring

23

front ring

24

inner ring

25

strip

26

Triangular recesses

27

Diamond-shaped recesses

28

Pasty mass

29

mounting direction

30

gap

A

Axial direction

automotive

motor vehicle

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19943446 A1 [0003]

Claims (14)

Electric machine ( 1 ), comprising a stator ( 3 ) with a laminated core ( 4 ), from which at least one axial end ( 6 ) each winding heads ( 5 ) an electrical winding ( 7 protrude), wherein at the at least one axial end ( 6 ) each by a housing ( 12 ) and / or a respective end shield ( 11 ) an annular receiving area ( 13 ), in which the winding heads ( 5 ) are arranged, characterized in that between the end windings ( 5 ) and an inner wall ( 14 ) of the recording area ( 13 ) at least one electrically insulating, permanently elastic material ( 15 ) is arranged, which the winding heads ( 5 ) and the inner wall ( 14 ) and thermally coupled and this has a heat transfer coefficient greater than 1 W / mK. Electric machine ( 1 ) according to claim 1, wherein the permanently elastic material ( 15 ) wholly or partly by a designed as a molded solid ( 25 ) provided on the winding heads ( 5 ) or to the winding heads ( 5 ) is created. Electric machine ( 1 ) according to claim 2, wherein the molded part ( 25 ) as a flexible strip ( 25 ) is configured, which in a rolled-out state recesses ( 26 . 27 ), which are designed such that the strip ( 27 ) when applying to the winding heads ( 5 ) a closed in the circumferential direction, wrinkle-free form ( 23 . 24 ) having. Electric machine ( 1 ) according to claim 3, wherein the recesses ( 26 . 27 ) have a triangular shape or a diamond shape. Electric machine ( 1 ) according to one of the preceding claims, wherein the permanently elastic material ( 15 ) wholly or partly by a plastically deformable mass ( 28 ). Electric machine ( 1 ) according to any one of the preceding claims, wherein the material ( 15 ) is self-adhesive. Electric machine ( 1 ) according to one of the preceding claims, wherein the electric machine ( 1 ) is designed as a vehicle electrical system generator. Motor vehicle (motor vehicle) with an electric machine ( 1 ) according to any one of the preceding claims. Method for producing an electric machine ( 1 ) according to one of claims 1 to 7, wherein a stator ( 3 ) with a laminated core ( 4 ), from which at least one axial end ( 6 ) each winding heads ( 5 ) an electrical winding ( 7 protrude), as well as for the at least one axial end ( 6 ) one each in a housing ( 12 ) and / or a respective end shield ( 11 ) formed, annular receiving area ( 13 ) for the winding heads ( 5 ) of the respective axial end ( 6 ), characterized by the steps: - providing an electrically insulating, permanently elastic material ( 15 ) at the winding heads ( 5 ) and / or in the respective recording area ( 13 ) and - at the at least one axial end ( 6 ) Inserting the winding heads ( 5 ) in the reception area ( 13 ) and thereby applying the permanently elastic material ( 15 ) with a contact pressure. Method according to claim 9, wherein the material ( 15 ) in whole or in part as a strip ( 25 ) with recesses ( 26 . 27 ) and the strip ( 25 ) before insertion on the winding heads ( 5 ) or in the recording area ( 13 ) is inserted so that the strip ( 25 ) after insertion at least one of the end windings ( 5 ) adjacent ring ( 22 . 23 . 24 ). Method according to claim 9 or 10, wherein at least part of the material is applied in the form of at least one blank or at least one mat in ready-to-use and / or pre-impregnated and / or pre-soaked form or in another beta state and by application of temperature and / or another ambient condition, in particular air humidity, and / or by at least one other phase-unspecific activator, in particular by chemical reaction and / or swelling and / or storage, is converted into a final state. Method according to one of claims 9 to 11, wherein the material ( 15 ) wholly or partly as a pasty mass ( 28 ) provided. Process according to claim 12, wherein the pasty mass ( 28 ) before insertion and / or insertion into spaces ( 30 ) between the winding heads ( 5 ) is distributed. A method according to claim 12 or 13, wherein a viscosity of the mass ( 28 ) upon insertion depending on a shear rate in the mass ( 28 ).

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