EP3911860A1

EP3911860A1 - Aerodynamic arm for an aircraft turbine engine casing

Info

Publication number: EP3911860A1
Application number: EP20705409.9A
Authority: EP
Inventors: Marc Missout
Original assignee: Safran Aircraft Engines SAS
Current assignee: Safran Aircraft Engines SAS
Priority date: 2019-01-14
Filing date: 2020-01-07
Publication date: 2021-11-24
Also published as: FR3091730A1; CA3123345A1; CN113260793A; FR3091730B1; US20220056804A1; CN113260793B; WO2020148493A1

Abstract

The invention relates to an aerodynamic arm (100) for an aircraft turbine engine casing, characterised in that it comprises: - a tubular outer shell (110) having a generally elongate shape extending substantially along an axis (A-A), the shell (110) comprising axial ends (112) for connecting to a turbine engine casing; - an electrically conductive core (120) extending inside the shell (110) and having ends for electrically connecting to each of the ends (112) of the shell (110); and - an insulating material (130) configured to occupy a space provided between the core (120) and the shell (110).

Description

DESCRIPTION

TITLE: AERODYNAMIC CRANKCASE ARM FOR A

AIRCRAFT TURBOMACHINE

Technical field of the invention

The present invention relates to the field of turbomachines. It relates to an aerodynamic casing arm for an aircraft turbomachine.

Technical background

The state of the art includes in particular the documents US-A1 - 2014/193249 and US-A1 -2012/266439.

Figure 1 shows a turbomachine 1 with double flow which comprises, conventionally centered on a longitudinal axis X, a fan S, a low pressure compressor 1 a, a high pressure compressor 1 b, an annular combustion chamber 1c, a turbine high pressure 1d, a low pressure turbine 1 e and an exhaust nozzle 1 h. The high pressure compressor 1b and the high pressure turbine 1d are connected by a high pressure shaft 2 and form with it a high pressure body (HP). The low pressure compressor 1a and the low pressure turbine 1e are connected by a low pressure shaft 3 and form with it a low pressure body (LP). Blower S is driven by a blower shaft 4.

The fan S delivers an annular air flow with a central annular part, called the primary flow FP, flowing inside a so-called primary stream delimited by an annular fairing 5a, which supplies the motor driving the fan S and an external annular part, called the secondary flow FS, which is ejected into the atmosphere while providing a large fraction of the thrust. The fan S is contained in a casing 5b delimiting, with the annular shroud 5a, a so-called secondary stream in which the secondary flow FS flows.

The hybridization of aircraft turbomachines uses very high electrical powers (of the order of 300 to 500 kVA) compared to the powers usually used for conventional turbomachines for aircraft (of the order of 60 kVA).

Despite the increase in the supply voltage (for example in a range of 500V to 1500V), the supply currents remain considerable for such power. Therefore, the section of the electrical conductors, which is proportional to the supply current to be passed through, is also larger. For example, the diameter of the cables, usually of the order of a few millimeters for conventional turbomachines, is of the order of several tens of millimeters for hybrid turbomachines.

However, in the case of electrical machines intended to be installed under the primary duct of the turbomachine, the electrical conductors must pass through the primary and secondary ducts of the turbomachine to convey the electrical energy between the electrical machines installed under the primary duct and the general aircraft electrical network. In addition, for the case of electrical machines intended to be installed in an inter-vein compartment of the turbomachine, also called “Core zone”, the electrical conductors must pass through at least the secondary vein. However, with their large section, the electrical conductors constitute an obstacle to the flow of air at least in the secondary stream of the turbomachine, thus degrading the internal aerodynamics of the turbomachine and thus compromising the performance of the turbomachine.

It is known practice to pass electrical supply conductors through fixed structural arms, also called easement passage arms, which pass through at least the secondary stream of the turbomachine. The thickness of such a structural arm is typically greater than 1.5 cm, and more generally greater than 2.5 cm.

These structural arms being generally hollow and occupied by fluid pipes, the space available to install electrical conductors of large cross section is limited and does not allow the circulation of large supply currents as required by hybrid turbomachines. . In addition, the number of structural arms passing through the secondary stream of the turbomachine is generally reduced, typically from two to four or five arms, which limits the total supply current that can flow through all the electrical conductors passing through the secondary stream.

The present invention proposes to provide a simple and effective solution to the problems mentioned above.

Summary of the invention

To this end, the invention relates to an aerodynamic casing arm for an aircraft turbomachine, characterized in that it comprises:

- an outer tubular casing having a generally elongated shape extending substantially along an axis, this casing comprising axial ends for connection to a turbomachine casing;

- an electrically conductive core extending inside the casing and having electrical connection ends at each end of the casing; and

- an insulating material configured to occupy a space between the core and the shell.

The aerodynamic arm according to the invention constitutes a simple and effective solution making it possible to pass electrical conductors of large diameter for the passage of high electrical powers while preserving the aerodynamic performance of the casing which it equips and the mechanical strength without increasing its capacity. mass. Indeed, the aerodynamic arm being intended to equip a turbomachine casing, it is intended to be traversed by a flow of air flowing inside the turbomachine. Therefore, it has an aerodynamic profile so as to limit airflow disturbances.

In addition, the aerodynamic arm is tubular and is crossed by a conductive core surrounded by an insulation. Thus, unlike the solutions of the prior art, all of the volume available inside the arm can be used to pass a large amount of electrical energy necessary for the operation of hybrid turbomachines.

The presence of the insulation between the core and the casing prevents any electrical contact between the conductive core and the outer casing of the arm, thus ensuring the integrity of the electrical connections of the turbomachine. According to the invention, for any section of the aerodynamic arm along a plane perpendicular to the axis of the envelope, a thickness of the aerodynamic arm is between 2 mm and 10 mm, and a chord length of the aerodynamic arm is between 30 mm and 150 mm.

Advantageously, for any section of the aerodynamic arm along a plane perpendicular to the axis of the casing, the insulating material has a minimum thickness of the order of 0.8 mm, preferably between 0.6 and 1.5 mm .

Advantageously, for any section of the aerodynamic arm along a plane perpendicular to the axis of the envelope, a thickness of the core is between 1 mm and 5 mm.

Advantageously, the ends of the core are configured to be connected by mechanical connections or welds to electrical conductors.

According to an exemplary embodiment, each of the axial ends of the casing comprises a flange for connecting or fixing to the turbomachine casing.

Thus, each aerodynamic arm can be attached to a turbomachine casing.

Preferably and advantageously, the insulating material is configured to withstand temperatures up to 200 ° C and is made from a liquid insulation, or an organic insulating powder polymerized by baking, or is configured to withstand temperatures. temperatures up to 800 ° C and is made from a mixture of mineral insulating powder and binder fired at high temperature.

Advantageously, the mineral insulating powder is Kapton®, Teflon® or magnesia resistant to the high temperatures of the environment of the turbomachines.

Advantageously, the binder is a ceramic binder.

The present invention also relates to an aircraft turbomachine, characterized in that it comprises at least ten aerodynamic arms having at least any one of the aforementioned characteristics, and preferably at least twenty aerodynamic arms, each aerodynamic arm forming part of a flow rectifier vane which crosses a secondary flow vein or a primary flow vein of the turbomachine.

The turbomachine according to the invention has the advantage of integrating and passing a greater amount of electrical energy through several (at least ten) aerodynamic arms of reduced dimensions. Thus, at least ten aerodynamic arms of reduced thickness are configured to equip a casing of the turbomachine, while preserving the mechanical strength and without increasing the mass of this casing. This can also make it possible to avoid the use of bulky arms to convey high electrical power.

The present invention finally relates to a manufacturing process for producing an aerodynamic arm according to the invention, this process comprising the steps of:

a) fabrication of the electrically conductive core;

b) manufacture of the envelope;

c) positioning of the core relative to the envelope while leaving a space;

d) adding the insulating material to the space between the casing and the electrically conductive core;

e) hardening of the insulating material to bond with the casing and the electrically conductive core.

The method according to the invention may include one or more of the following characteristics, taken in isolation from each other or in combination with each other:

- in step b), the envelope is produced by additive manufacturing;

- steps b) and c) are performed simultaneously, making the envelope directly around the core;

- the core and an interior surface of the envelope are produced at the same time by additive manufacturing;

- In step c), the insulating material is either in the form of liquid insulation or of an insulating powder, or in the form of a mixture of inorganic insulating powder and of binder; - step c) further comprises either a polymerization of the liquid insulation or of the insulation powder, or a baking of the mixture of inorganic insulating powder and binder.

Brief description of the figures

Other characteristics and advantages of the invention will become apparent on reading the detailed description which follows, for the understanding of which reference is made to the appended drawings in which:

[Fig. 1] Figure 1, already discussed, is a schematic sectional view of a turbomachine;

[Fig. 2] Figure 2 is a perspective view of a turbomachine casing;

[Fig. 3] Figure 3 is a detail view of an exemplary embodiment of an aerodynamic arm according to the invention;

[Fig. 4] Figure 4 is a cross-sectional view of the aerodynamic arm illustrated in Figure 3.

Detailed description of the invention

In this presentation, the terms "upstream", "downstream" are used with reference to the direction of gas flow in an aircraft turbomachine. The terms “internal” and “external” are defined with respect to a longitudinal axis of the turbomachine. The terms "axial", "interior" and "exterior" are defined with reference to the positioning of the constituent elements of the aerodynamic arm according to the invention.

With reference to FIG. 2, a structural element of the turbomachine 1 designated intermediate casing 6 comprising two coaxial annular rows of blades constituting an internal vane located in the primary flow FP and an external vane located in the secondary flow FS. More specifically, the intermediate casing 6 comprises a hub 7 intended to be traversed by the BP shaft 3, an internal ring 8 for separating the primary FP and secondary FS flows, an external annular ring 9 located at a nacelle of the turbomachine, aerodynamic radial arms 10 in the form of fins extending radially between the ring 8 and the outer shell 9 and internal radial arms 11 for connection between the hub 7 and the ring gear 8. The arms 10 form the external blade and the arms 11 form the internal blade. Radial arms 12 can also be placed in the external vane and transmit part of the forces between the motor and its support, the arms 12 being structural arms. The arms 10 of the intermediate casing can take the form of a flow straightening blade to straighten the secondary flow FS flowing in the secondary stream, in the X axis of the turbomachine 1 downstream of the fan s. The arms 10 then constitute OGV which is the acronym in English for Outlet Guide Vane. A ring of fixed fins (not shown) is generally disposed between the fan S and the arms 11 of the intermediate casing, to straighten the primary flow FP flowing in the primary stream, in the X axis of the turbomachine 1. These fins are generally referred to by the term IGV which is the acronym in English for Inlet Guide Vane.

The intermediate casing 6 has a structural function insofar as the forces are transmitted through it; in particular the means for fixing the turbomachine 1 to the structure of the aircraft are integral with the intermediate casing 6.

An exemplary embodiment of the aerodynamic arm 100 according to the invention is illustrated in Figures 3 and 4.

The aerodynamic arm 100 comprises:

- an outer envelope 110;

- an electrically conductive core 120; and

- an insulating material 130.

The envelope 110 is tubular. It has a tubular body 111 of generally elongated shape extending substantially along an axis A-A and axial ends 112 for connection to a casing, such as for example an intermediate casing 6 of a turbomachine 1.

The electrically conductive core 120 and the insulating material 130 are trapped in an interior cavity delimited by an interior surface of the casing 110.

In cross section, the body 111 of the envelope 110 has an aerodynamic profile as can be seen in FIG. 4. The body 111 thus has a leading edge 111 a, a trailing edge 111 b, a lower surface 111 c and an upper surface 111 d.

The aerodynamic arms 100 according to the invention are configured to equip a casing, in particular an intermediate casing for an aircraft turbomachine. For this, each of the axial ends 112 of the casing 110 has a flange 112a for connecting or fixing to the housing. Thus, each aerodynamic arm can be attached to the intermediate casing 6, for example by welding the flanges 112a of the casing 110 to the inner ring 8 and the outer shell 9 of the casing of the turbomachine.

The casing 100 is made of any material having the necessary abrasion resistance properties. It is for example made of metal.

The envelope 100 has a thickness guaranteeing the mechanical strength of the aerodynamic arm 100.

The core 120 extends along the axis AA inside the envelope 110. It has electrical connection ends (not shown) at each of the ends 112 of the envelope 110. The connection ends of the core 120 are configured to be connected by mechanical connections or welds to electrical conductors of the turbomachine, either for example to the general electrical network of the aircraft or to electrical machines installed under the primary stream.

The electrical connection ends of the core 120 are either protuberances of the core 120, or separate elements that can be attached by screwing to the ends of the core 120 when the arms 100 are mounted on the casing 6 (for example at means of pods).

The core is made of any electrically conductive material. It is for example made of copper or aluminum, depending on the ambient temperature of the environment in which the aerodynamic arms 100 are installed. The core 120 may for example consist of a metal strip of rectangular section (as illustrated in FIG. 4), with a width (thickness of the strip of rectangular section) of between 1 mm and 3 mm and a length of section of between 10 mm and 50 mm. In the case where the electrical connection ends of the core 120 include mechanical connections for connection to conductors electrical of the turbomachine, these mechanical links can be formed with the core 120 by machining, by molding, or by additive manufacturing.

The insulating material 130 able to occupy the space between the core 120 and the casing 110 can be chosen according to the ambient temperature of the environment in which the aerodynamic arms 100 are installed.

According to an exemplary embodiment, the insulating material 130 can be obtained from either a liquid insulator or an organic insulating powder polymerized by baking, the insulating material thus being configured to withstand temperatures of up to at 200 ° C.

According to another exemplary embodiment, the insulating material 130 can be obtained from a mixture of a mineral insulating powder and a binder cooked at high temperature, the insulating material thus being configured to withstand temperatures of up to at up to 800 ° C.

The mineral insulating powder can be Kapton® or Teflon® which have very good dielectric properties and good temperature resistance which can withstand temperatures up to 200 ° C.

The insulating mineral powder can also be magnesia or aluminum oxide. The mineral insulating powder has better properties of resistance to high temperatures. Combined with a ceramic binder such as, for example, mineral insulating powder can withstand temperatures of up to 800 ° C.

Thus, for temperatures of the order of 200 ° C to 300 ° C, the binder can be a polymer resin of the thermosetting type, and for higher temperatures, the binder can be an oxide composite in the form of a slip, such as Ox / Ox.

The shape of the envelope 110 is thus adapted to the flow of the air flow in the turbomachine 1 in operation, the aerodynamic profile of the envelope 110 thus providing a straightening function for the flow of air in the primary and secondary veins.

The arms 100 can thus take the form of flow straightening vanes thus ensuring a function of straightening the flow downstream of the fan S, in the primary stream they can constitute IGVs, or in the secondary stream they can constitute OGV, the function of conduction of electrical energy then being ensured by parts having an aerodynamic role.

The aerodynamic arms 100 thus have, in the configuration of the invention, both an aerodynamic function of rectifier of the secondary air flow coming from the fan S in the X axis of the turbomachine and an electrical conduction function, with possibly a structural function if at least some arms are provided sufficiently thick and / or rigid to participate in the mechanical strength of the assembly formed by the arms and the rings or rings between which the arms extend radially. Thus, in accordance with the invention, advantageously compared to the arms of the prior art, the volume available inside the arms 100 is used to pass electrical energy through the primary and secondary veins. , between the general electrical network of the aircraft and the electrical machines installed under the primary duct.

Thus, an aircraft turbomachine comprising a plurality of arms 100 according to the invention allows a large total electrical current to pass between the electrical machines and the general electrical network of the aircraft while maintaining good performance.

The proposed solution applies in particular to turbomachines for aircraft in which, in order to pass a large electric current through a primary or secondary flow stream, it is necessary in the current state of the art to install electrical conductors of diameter important, for example greater than 5 mm, in the passage arms of easements.

An aircraft turbomachine according to the invention thus comprises at least ten aerodynamic arms 100 and, preferably, at least twenty aerodynamic arms 100. Each aerodynamic arm 100 is part of a set of OGVs or IGVs constituting rectifier blades. of a flow which passes respectively through a secondary flow stream or a primary flow stream of the turbomachine downstream of a fan.

The aircraft turbomachine according to the invention comprises, more preferably, between 30 and 70 aerodynamic arms 100 according to the invention, this number varying according to the type of engine of the turbomachine.

For any section of the aerodynamic arm 100 along a plane perpendicular to the axis AA of the envelope 110, a maximum thickness Ep of the aerodynamic arm 100 is preferably between 2 mm and 10 mm, and a chord length L of the aerodynamic arm 100 is preferably between 30 mm and 150 mm.

For any section of the aerodynamic arm 110 along a plane perpendicular to the axis A-A of the casing 110, a thickness of the core 120 is preferably between 1 mm and 5 mm.

According to an interesting but in no way limiting example of an embodiment, it is sought to cause the assembly of the aerodynamic arms 100 to circulate a current of 1.8 kA (corresponding to a power of 1 MW under a supply voltage of 540 V of the turbomachine) , which requires a total conductor section of 10 cm ² . In the case of a turbomachine comprising 66 aerodynamic arms 100, this corresponds to a section of the electrically conductive core 120 of the order of 15 mm ² , ie for a core 120 of rectangular section as illustrated in FIG. 4 , a width of 1 mm and a length of 15 mm. However, the electrically conductive core 120 may have a section having any shape, and in particular a shape relatively identical to that of the casing 110 of the aerodynamic arm 100.

The minimum thickness e to be observed of the insulating material 130 between an external surface of the core 120 and the internal surface of the casing 110 depends on the supply voltage of the turbomachine. Thus, for a supply voltage of 540 V, the insulating material 130 has a minimum thickness e of the order of 0.8 mm. More generally, the minimum thickness e will preferably be between 0.6 mm and 1.5 mm.

Thus, for such a configuration, the aerodynamic arm 100 has, for example, a thickness Ep of the order of 5 mm and a total chord length L of between 60 mm and 80 mm.

The method for producing the aerodynamic arm 100 according to the invention according to the invention comprises the following steps:

a) fabrication of the electrically conductive core 120;

b) manufacture of the envelope 1 10;

c) positioning of the core 120 relative to the casing 1 10 by leaving a space; d) addition of the insulating material 130 in the space formed between the casing 110 and the electrically conductive core 120;

e) hardening of the insulating material 130 to bond with the casing 110 and the electrically conductive core 120.

As described below, the core 120 can be made before or after the shell 110, or simultaneously; and the step of curing the insulating material 130 differs depending on the type of insulating material 130 used.

According to an interesting but in no way limiting embodiment, the aerodynamic arm 100 according to the invention is produced according to a process comprising the following steps:

- The core 120 is manufactured by any process known per se, such as for example by a process of drawing, machining, stamping, ...;

- the core 120 is then positioned on an additive manufacturing support plate;

- the casing 110 is then produced by additive manufacturing, around the electrically conductive core 120, leaving a space between an outer surface of the electrically conductive core 120 and an inner surface of the casing 110;

- the space formed between the outer surface of the electrically conductive core 120 and the inner surface of the casing 110 is filled with the insulator which may be in the form of either a liquid insulator or an organic insulating powder , or a mixture of inorganic insulating powder and of binder, for example ceramic;

- the assembly is then heated, this step making it possible either to polymerize the insulation in the case of a liquid insulation or an organic insulating powder, or to bake the insulation in the case of a mixture of insulating powder mineral and binder, for example ceramic in order to bind the powder and the binder, so as to form the insulating material 130.

According to another embodiment, when the insulating material 130 is in the liquid state when it is cast between the conductive core 120 and the casing 110, this liquid state is obtained either by melting the insulating material ( in the case of thermoplastic insulation) or by nature (in the case of ceramic insulation). The transition to the solid state of the material insulation is then obtained, either by cooling or by firing the ceramic slip, for example in an oven provided for this purpose.

The choice of one or the other solution depends on the temperature at which the aerodynamic arm 100 will be required to operate, in other words, according to the type of turbomachine that it will be required to equip (an insulating material of the thermoplastic type is not for example not withstanding a temperature higher than 100 ° C).

The envelope 110, and therefore the arm 100, can have complex inner and outer shapes due to the presence of several degrees of curvature giving it a twisted appearance around the axis A-A. The envelope 110 can be produced by LMD (acronym for Laser Metal Deposition) technology of additive manufacturing, consisting in using a laser beam to generate on a metallic material a layer of molten material to which material is then added. to merge and grow the layer, the supply being made for example in the form of a powder or a wire made of the material. The laser thus fuses, layer after layer, the surface of the component being manufactured with the additional material added.

In this way, the casing 110 is produced directly around the electrically conductive core 120, leaving a space between the outer surface of the electrically conductive core 120 and the inner surface of the casing 110 intended to receive the insulating material. 130. The above-mentioned steps b) and c) then being carried out simultaneously.

On the same platform of an additive manufacturing system, it is possible to provide for the simultaneous manufacture of several aerodynamic arms 100, in order to improve the productivity of the manufacturing process.

It is also envisioned that the casing 110, and therefore the arm 100, have interior and exterior shapes that are substantially rectilinear (not twisted). In this case, the envelope 100 can be produced by any method known per se, such as for example by the SLM technology (acronym for Selective Laser Melting in English) of additive manufacturing, consisting in fusing the powder by means of a high energy beam such as a laser beam. In practice, a powder bed is deposited on a support plate and is scanned by the laser beam to selectively melt the powder, and thus manufacture a part layer by layer, a third layer of fused powder being arranged above a second layer which is itself placed on top of a first layer.

The core 120 is then attached to the interior of the casing 110 thus produced, by leaving a space between the outer surface of the core 120 and the inner surface of the casing 110. This space is then filled as described above. and the assembly is heated so as to form the insulating material 130.

It is also conceivable to produce by additive manufacturing both the electrically conductive core 120 and the inner surface of the casing 110. LMD technology in particular makes it possible to produce together two parts each formed from a different metallic material, for example. from two spools of threads made of the two materials.

Moreover, in all cases, in order to limit the loss of aerodynamic pressure, the method for producing the aerodynamic arm 100 according to the invention may also include a step of polishing an outer surface of the casing 100.

In addition, the additive manufacturing technique makes it possible to create an envelope 110 having doubly complex shapes, namely at the level of the exterior surface and the interior surface of the envelope 110.

Claims

1. Aerodynamic casing arm (100) for an aircraft turbomachine (1), comprising:

- an outer tubular casing (110) having a generally elongated shape extending substantially along an axis (AA), this casing (110) comprising axial ends (112) for connection to a casing (6) of the turbomachine (1);

- an electrically conductive core (120) extending inside the casing (110) and having electrical connection ends at each end (112) of the casing (110); and

- an insulating material (130) configured to occupy a space formed between the core (120) and the casing (110), characterized in that for any section of the aerodynamic arm (100) along a plane perpendicular to the axis ( AA) of the casing (110), a maximum thickness (Ep) of the aero arm (100) is between 2mm and 10mm, and a chord length (L) of the aero arm (100) is between 30mm and 150 mm.

2. Aerodynamic arm (100) according to the preceding claim, characterized in that the insulating material (130) has a minimum thickness (e) of the order of 0.8 mm, preferably between 0.6 and 1.5 mm.

3. Aerodynamic arm (100) according to one of the preceding claims, characterized in that a thickness of the core (120) is between 1 mm and 5 mm.

4. Aerodynamic arm (100) according to one of the preceding claims, wherein the ends of the core (120) are configured to be connected by mechanical connections or welds to electrical conductors.

5. Aerodynamic arm (100) according to one of the preceding claims, wherein each of the axial ends (112) of the casing (110) comprises a flange (112a) for connecting or fixing to the casing (6) of the turbomachine ( 1).

6. aerodynamic arm (100) according to one of the preceding claims, wherein the insulating material (130) is configured to resist at temperatures up to 200 ° C and is made from a liquid insulation or organic insulating powder cured by curing, or is configured to withstand temperatures up to 800 ° C and is manufactured at from a mixture of a mineral insulating powder and a binder cooked at high temperature.

7. Aerodynamic arm (100) according to the preceding claim, wherein the mineral insulating powder is Kapton®, Teflon® or magnesia.

8. Aerodynamic arm (100) according to one of claims 6 or 7, wherein the binder is a ceramic binder.

9. Turbomachine (1) of a bypass aircraft, characterized in that it comprises at least ten aerodynamic arms (100) according to any one of claims 1 to 8, and preferably at least twenty aerodynamic arms (100) , each aerodynamic arm (100) forming part of a flow rectifier blade which passes through a secondary flow stream or a primary flow stream of the turbomachine.

10. Manufacturing process for producing an aerodynamic arm (100) of the casing according to one of claims 1 to 8, characterized in that it comprises the following steps:

a) fabrication of the electrically conductive core (120);

b) manufacturing the casing (110);

c) positioning the core (120) relative to the casing (110) while leaving a space;

d) adding the insulating material (130) to the space between the shell (110) and the electrically conductive core (120);

e) hardening the insulating material (130) to bond with the casing (110) and the electrically conductive core (120).

11. Method according to the preceding claim, characterized in that in step b), the casing (110) is produced by additive manufacturing.

12. The method of claim 10 or 11, characterized in that steps b) and c) are performed simultaneously, by making the envelope (110) directly around the core (120).

13. The method of claim 10, characterized in that the core (120) and an inner surface of the casing (100) are produced at the same time by additive manufacturing.

14. Method according to one of claims 10 to 13, characterized in that in step c), the insulating material (130) is either in the form of liquid insulation or of an insulating powder, or in form of a mixture of mineral insulating powder and binder.

15. Method according to the preceding claim, characterized in that step c) further comprises either a polymerization of the liquid insulation or of the insulating powder, or a baking of the mixture of mineral insulating powder and binder.