Method for manufacturing a component for a spark plug and spark plug

Abstract

A method for manufacturing a component of a central pin (20) and a corresponding intermediate electrode carrier (13) or intermediate electrode (6) for a spark plug (1) that can be used to ignite a combustible air-fuel mixture in an internal combustion engine, wherein: a piece (19) of wire or rod is provided, which piece (19) preferably has a core (21) of a first material along its length, the core (21) being surrounded by an outer layer (22) of a second material, the second material being different from the first material, wherein the core is exposed at one end of the piece of wire or rod; the corresponding intermediate electrode carrier (13) or intermediate electrode (6) is provided at the said one end of the piece of wire or rod (19); a high-energy beam (preferably, a laser beam) is directed onto the exposed core (21), and powder is melted onto the exposed core (21) by the high-energy beam such that, after re-solidification of the material of the core (21) and the powder, a microstructure composed of the material of the core (21) and the powder is formed in the contact area (18) between the powder and the exposed core (21), and the core (21) is covered at one end of the piece of wire or rod by the re-solidified powder (25).

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a component of a center pin for a spark plug and a corresponding intermediate electrode carrier or intermediate electrode having features according to the present invention, a method for manufacturing a spark plug, a component of a center pin and an intermediate electrode carrier for a spark plug having features according to the present invention, and a spark plug having such a component. Background Art

[0002] Spark plugs are known from various embodiments of the prior art. Due to efforts to increase the service life requirements, requirements regarding airtightness and temperature management (i.e., achieving appropriate heat transfer between the spark plug on the one hand and the cylinder head or on the other hand the spark plug sleeve) have become more important.

[0003] Known spark plugs have an intermediate electrode and at least one mass electrode, the intermediate electrode being arranged centrally with respect to the longitudinal axis of the spark plug, and the at least one mass electrode being radially remote from the intermediate electrode. An ignition gap is formed between the adjacent region (ignition region) of the intermediate electrode and the at least one mass electrode.

[0004] It is known to form the intermediate electrode in at least two parts, wherein the ignition zone is formed by a body of precious metal arranged on an intermediate electrode carrier. The respective bodies of precious metal are connected to the mass electrode carrier and the intermediate electrode carrier by welding joints accordingly. Such spark plugs are disclosed, for example, by EP 0 859 436 A1 or EP 3 068 001 A1.

[0005] Spark plugs are manufactured, for example, by a laser welding process.

[0006] Spark plugs are exposed to high temperatures and high pressures during the operation of a combustion engine because at least one part of the spark plug is in direct contact with the combustion chamber and thus directly with the combustion process. Over time, this leads to the removal of the electrode material and thus to a reduction in the service life. Another disadvantage of spark plugs known from the prior art is the change in the regions of the respective face sides and face areas of the electrodes, in particular the spark plug pin and the body of precious metal, facing the combustion chamber (in the ignition direction), which is caused by thermal corrosion or oxidation.

[0007] The spark plug is installed in the cylinder head or spark plug sleeve of an internal combustion engine by screwing an external thread portion (or external thread) of the spark plug body, which at least partially surrounds the ignition device, into an internal thread portion on the cylinder head or spark plug sleeve in such a way that the ignition device is arranged at the end of the spark plug facing the combustion chamber.

[0008] Heat is transferred from the combustion in the combustion chamber to the spark plug, and this heat is dissipated to the cylinder head or the spark plug sleeve through the external thread. Therefore, it is important to have a certain heat conduction between the external thread and the cylinder head or the spark plug sleeve, because it is well known that insufficient heat dissipation leads to a reduction in the life of the spark plug.

[0009] In the prior art, attempts have been made to arrange the spark plug as far as possible outside the combustion chamber. However, this has the disadvantage that the spark position of the spark plug is not arranged as far as necessary in the combustion chamber for the sufficient ignition of the air-fuel mixture.

[0010] Another strategy of the prior art lies in dissipating the amount of heat introduced into the components of the spark plug to the cylinder head as quickly and sufficiently as possible (usually using a spark plug sleeve). For this purpose, the intermediate electrode carrier usually has a core of a material with good thermal conductivity (such as, for example, copper). To protect the core, it is embedded in a material with good heat and corrosion resistance, so that the core is shielded from the influence of the combustion gases (see US 4,575,343 A). The assembly of the core and the shielding material is called the center pin.

[0011] As described in US 4,575,343 A, for example, the center pin is manufactured by pressing copper into a nickel pin by cold forming, which is expensive, and the life of the spark plug with such a center pin is usually not satisfactory. Different ways of manufacturing the center pin are shown in US 3,356,882 A, in which a plurality of electrode rods composed of a copper core and a cover of Inconel are welded to an Inconel strip. Using a punch, the capped electrodes are sheared from the Inconel strip.

[0012] Regarding the manufacturing techniques of the two prior arts, the exact position of the copper core is uncontrollable, resulting in unknown thermal properties and thus accidentally changing the life of the spark plug. Summary of the Invention

[0013] The object of the present invention is to provide a method for manufacturing an assembly of a center pin for a spark plug and a corresponding intermediate electrode carrier or intermediate electrode, a method for manufacturing a spark plug, an assembly of a center pin for a spark plug and a corresponding intermediate electrode carrier or intermediate electrode, and a spark plug having such an assembly, wherein the resulting corresponding assembly and spark plug are easier to manufacture and preferably have an increased life.

[0014] This is achieved by a method having the features according to the present invention, a method for manufacturing a spark plug including such a method, an assembly having the features according to the present invention, and a spark plug having such an assembly. Some advantageous embodiments of the present invention are defined in the dependent claims.

[0015] The present invention provides a method for manufacturing a component of a center pin and a corresponding intermediate electrode carrier or intermediate electrode for a spark plug, which can be used to ignite a combustible air-fuel mixture in an internal combustion engine, characterized in that:

[0016] - providing a piece of wire or rod, which preferably has a core of a first material along its length, the core being surrounded by an outer layer of a second material different from the first material, wherein the core is exposed at one end of the piece of wire or rod - arranging the corresponding intermediate electrode carrier or intermediate electrode at the said one end of the piece of wire or rod - guiding a high-energy beam (preferably a laser beam) to the exposed core, and melting powder onto the exposed core by means of the high-energy beam, such that after re-solidification of the material of the core and the powder, a microstructure composed of the material of the core and the powder is formed in the contact area between the powder and the exposed core, and the core is covered by the re-solidified powder at one end of the piece of wire or rod.

[0017] It should be noted that the second and third steps in the above steps do not have to be carried out in a given order. As will be explained below, it is even possible to provide the corresponding intermediate electrode carrier or intermediate electrode by providing molten powder, such that there is no distinct second step or third step.

[0018] The technique of melting powder onto a given surface by means of a high-energy beam (usually a laser beam) is well known in the art (commonly referred to as laser metal deposition). For the present invention, it is preferred to inject the powder into the laser beam through a powder nozzle. However, it is also possible to first coat the powder onto the surface and then apply the laser beam to the powder on the surface to melt it. The coating and melting of the powder can be carried out layer by layer, such that new powder is melted onto the layer of re-solidified powder.

[0019] The advantage of using a piece of wire or rod that preferably has a core of a first material surrounded by an outer layer of a second material different from the first material along its length is that, at one end of the piece of wire or rod where the core is exposed, in a plane perpendicular to the extension of the wire or rod, the material of the core and the material of the outer layer form a flat surface. It is possible to attach the intermediate electrode carrier or the intermediate electrode itself (with or without removing material from the said flat surface) to the said flat surface or to the outer layer of the wire or rod. This is advantageous because by choosing the extension of the intermediate electrode carrier or the intermediate electrode perpendicular to the said flat surface, the distance between the said flat surface (and thus the surface of the material of the core) and the seat for the intermediate electrode carrier of the intermediate electrode or the intermediate electrode itself can be selected in a reproducible manner. The re-solidified powder is used to prevent the core from being worn by the conditions in the combustion chamber by sealing the exposed surface of the core. Due to the contact area where there is a tight contact between the re-solidified powder and the material of the core, heat from the combustion chamber can be efficiently transferred from the re-solidified powder to the core of the center pin via the contact area.

[0020] In a first variant of the invention, it is possible to attach the respective intermediate electrode carrier or intermediate electrode to (preferably weld to) the central pin independently of the coating powder, such that the powder serves as the material for sealing the core and possibly seals the weld between the respective intermediate electrode carrier or intermediate electrode and the central pin, but the central pin itself does not form part of the respective intermediate electrode carrier or intermediate electrode.

[0021] In a second variant of the invention, the respective intermediate electrode carrier or intermediate electrode can be (at least partially) constructed by coating with powder, such that the re-solidified powder forms at least part of the respective intermediate electrode carrier or intermediate electrode (and of course seals the exposed core).

[0022] Preferably, the intermediate electrode is made of a noble metal, in particular, the intermediate electrode is a foil composed of a noble metal.

[0023] The invention also provides an assembly of a central pin for a spark plug and a respective intermediate electrode carrier or intermediate electrode, the spark plug being usable for igniting a combustible air-fuel mixture in an internal combustion engine, wherein:

[0024] - the central pin comprises a piece of wire or bar, which preferably has a core of a first material along its length, the core being surrounded by an outer layer of a second material, the second material being different from the first material,

[0025] - the respective intermediate electrode carrier or intermediate electrode is attached to one end of the piece of wire or bar,

[0026] - the core of the central pin is covered with a material provided in the form of molten powder, and the material is re-solidified such that a microstructure composed of the material of the core and the powder exists in the contact area between the re-solidified powder and the core.

[0027] Protection is also sought for a spark plug including such an assembly.

[0028] The use of a piece of wire or bar simplifies the manufacture of an assembly of a central pin for a spark plug and a respective intermediate electrode carrier or intermediate electrode, as well as the manufacture of a spark plug having such an assembly, without reducing the lifespan or even showing an increase in lifespan.

[0029] Wires or bars of the type usable in the invention are commercially available, for example in the form of so-called coated wires or coated bars, which are a combination of two materials in the form of a wire or bar (for example a nickel-coated copper wire or bar).

[0030] Alternatively, they can be easily produced by using a wire or rod having a hollow core made of a second material, into which a wire or rod made of the first material is drawn. To ensure a tight fit, the assembly can be drawn to produce the wire or rod having a core of the first material surrounded by an outer layer of the second material.

[0031] Pieces of wire or rod of a desired length can be obtained, or the pieces of wire or rod can be provided with such a length that several pieces of a desired length can be obtained, for example, by cutting a longer piece of wire or rod. If necessary, before attaching or forming the body, one end of the wire or rod on which the body is to be attached or formed can be refurbished, for example, by grinding, turning, milling, grinding and / or polishing the end face of the wire or rod.

[0032] The core should be completely covered with re-cured powder to seal it relative to the combustion chamber and thus protect it from the combustion gases. It is advantageous if the core is completely covered with re-cured powder.

[0033] A preferred embodiment of the present invention provides that the step of providing the intermediate electrode carrier at the one end of the piece of wire or rod includes the step of attaching or forming on the one end of the piece of wire or rod a body (preferably, the body is composed of at least one metal such as nickel), the body

[0034] - either forms the intermediate electrode carrier, or

[0035] - serves as an intermediate product for the intermediate electrode carrier, wherein the intermediate electrode carrier is obtained from this intermediate product by at least one additional manufacturing step.

[0036] This preferred embodiment contemplates in a first alternative that the body for attaching or forming on the one end of the piece of wire or rod directly forms the intermediate electrode carrier ready for mounting the intermediate electrode. In this case, the body can be manufactured independently of the piece of wire or rod to have a desired size. The body can have a shoulder, which can be part of or form the entire mounting surface for attaching the intermediate electrode to the intermediate electrode carrier.

[0037] In a second alternative, this preferred embodiment contemplates using the body for attaching or forming on the one end of the piece of wire or rod as an intermediate product for the intermediate electrode carrier, wherein the intermediate electrode carrier is obtained from this intermediate product by at least one additional manufacturing step. In this case, the body indirectly forms the intermediate electrode carrier in the sense that at least one additional manufacturing step (possibly several manufacturing steps) is necessary to obtain the intermediate electrode carrier ready for mounting the intermediate electrode.

[0038] In this second alternative, the body may be integrally attached to the one end of the wire or rod (e.g., by welding, preferably laser beam welding), and at least one additional step may be performed after attaching the body. However, it is preferred to use powder deposition techniques for forming the body on the end of the piece of wire or rod.

[0039] In a first embodiment of such powder deposition techniques, the body is fabricated in at least one layer such that for each layer, powder is deposited on the one end of the piece of wire or rod and melted - preferably by a high energy beam (e.g., a laser beam or an electron beam) - and re-solidified to form the at least one layer.

[0040] In a second embodiment of such powder deposition techniques, a laser beam is directed to the one end of the piece of wire or rod to melt its surface, and powder is introduced into the weld pool whose surface has been melted by the laser beam such that the powder melts and joins with the melted surface. The powder is deposited until the body is fabricated.

[0041] As the powder, preferably a corrosion-resistant nickel powder (e.g., available under the trade name Inconel or Inconel is used) or other powder materials suitable for the laser material deposition process.

[0042] Regarding both the first alternative (the body directly forms the intermediate electrode carrier) and the second alternative (the body serves as an intermediate product) of the preferred embodiment, it may be provided that the body has larger dimensions relative to at least one direction, preferably relative to the longitudinal axis of the wire or rod, and the said additional manufacturing steps for obtaining the intermediate electrode carrier from the intermediate product include at least one step in which material is removed from the body to obtain a body having reduced dimensions, preferably dimensions corresponding to those of the intermediate electrode carrier.

[0043] Regarding both the first alternative and the second alternative of the preferred embodiment, it may be provided that the said additional manufacturing steps for obtaining the intermediate electrode carrier from the intermediate product include at least one step in which a shoulder is formed on the body. The shoulder may be part of the mounting surface for attaching the intermediate electrode to the intermediate electrode carrier or may form the entire mounting surface.

[0044] In a preferred embodiment combinable with each of the foregoing embodiments, the mounting surface of the intermediate electrode carrier for the intermediate electrode has a predefined distance to the core relative to the longitudinal axis of the wire or rod. By selecting a specific predefined distance, for example at least 0.05 mm, preferably greater than 0.1 mm, most preferably greater than 0.2 mm, it is possible to obtain a spark plug in a repeatable manner which, compared to spark plugs in the prior art, has an intermediate electrode with a lower temperature during operation. To ensure good heat dissipation, the distance between the intermediate electrode and the core of the wire or rod should be as small as possible. However, to protect the core from the conditions in the combustion chamber, this distance should not be too small. With this embodiment of the invention, an optimal predefined distance can be found (for example, by means of an experimental test series in which different distances are tried and the resulting temperatures are observed, or by calculation or computer simulation), and it is possible to manufacture spark plugs with this distance in a repeatable manner.

[0045] Regarding this embodiment, it is possible to control the distance between the core of the first material and the material covering the core (in other words, to control the distance from the mounting surface of the intermediate electrode carrier to the core). Compared to the prior art, it is possible to have a smaller distance to improve heat transfer while still ensuring that the distance is large enough to protect the core material.

[0046] For example, it is possible to measure the length of the piece of wire or rod before applying the body from one end to the other. Using this information, it is then possible to remove as much material as desired from the body after applying the body to obtain the desired predefined distance. Alternatively or additionally, one end of the piece or rod can be provided with a mark.

[0047] Components and spark plugs manufactured according to this embodiment of the invention show that during operation in a combustion engine, the heat transfer from the intermediate electrode to the cylinder head increases, resulting in a lower temperature of the intermediate electrode and thus an increased lifespan. They are enabled for higher power densities in the combustion chamber.

[0048] By way of example, compared to the prior art, it has been found that the temperature of the intermediate electrode is reduced by up to 80 - 100 °C.

[0049] By way of example, such a spark plug is enabled for power densities above 22 bar BMEP.

[0050] By way of example, the pre-defined distance from the mounting surface of the intermediate electrode carrier to the core can be obtained by using a body that is at least dimensionally larger relative to the longitudinal axis of the wire or rod (e.g., as provided by one of the foregoing embodiments), and the material of the body is removed along a direction parallel to the longitudinal axis of the wire or rod (e.g., by cutting, turning or grinding) such that the pre-defined distance is formed. Alternatively, of course, it will be possible to form a body that already has the desired distance when combined with the wire or rod.

[0051] In an embodiment of the invention, a piece of wire or rod (preferably, a coated wire) is used, wherein the core is composed of a material having a higher thermal conductivity than the outer layer, and the core preferably comprises or consists of copper or a copper alloy. Other materials having a high thermal conductivity, such as silver or gold, can be used.

[0052] In an embodiment of the invention, a piece of wire or rod (preferably, a coated wire) is used, wherein the outer layer is composed of a material having a higher heat corrosion resistance than the core, and the outer layer preferably comprises or consists of nickel or a nickel alloy.

[0053] In an embodiment of the invention, the intermediate electrode carrier comprises or consists of a metal preferably nickel.

[0054] To ensure the good functioning of the center pin (i.e., the wire or rod having a body that serves as the intermediate electrode carrier), it is envisaged in one embodiment that there is a layer with a minimum thickness on the front end portion of the core. The layer thickness can be at least 0.05 mm, preferably at least 0.1 mm. In some embodiments, the layer can have a thickness of at least 0.2 mm.

[0055] Embodiments of the spark plug further comprise:

[0056] - an ignition device that is arranged at the end of the spark plug facing the combustion chamber when the spark plug is installed in an internal combustion engine, and the ignition device comprises an intermediate electrode and a ground electrode,

[0057] - a wall that preferably at least partially surrounds the ignition device, and

[0058] - a sealing zone for sealing the combustion chamber relative to the environment,

[0059] wherein the wall comprises a sealing zone at the end of the wall that faces the combustion chamber when the spark plug is installed in an internal combustion engine, and preferably, the sealing zone is the end portion of the wall that faces the combustion chamber when the spark plug is installed in an internal combustion engine, and in particular, the sealing zone is designed as an inclined surface. However, it must be noted that the present invention can be used with all types of spark plugs regardless of the type of sealing.

[0060] It should be understood that the structural features of the spark plug or any of its components discussed in connection with the method of the invention are also intended to relate to the assembly or the spark plug. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Additional details and advantages of the present invention are apparent from the drawings and the following description of the drawings. The drawings show:

[0062] Figure 1 A cross-sectional view showing an embodiment of an assembly manufactured according to and by way of an embodiment of the method of the present invention;

[0063] Figure 2 A cross-sectional view showing a piece of wire or rod suitable for an assembly manufactured according to and by way of an embodiment of the method of the present invention;

[0064] Figure 3a 、 Figure 3b A cross-sectional view and an isometric cross-sectional view showing a spark plug according to an embodiment of the present invention;

[0065] Figure 3c A cross-sectional view and a detailed view thereof showing another embodiment of the present invention;

[0066] Figure 4 A cross-sectional view showing a wire or rod suitable for an assembly according to the present invention;

[0067] Figure 5a 、 Figure 5b A side view and a cross-sectional view showing an assembly according to the present invention, wherein the body has been formed as an intermediate product on a wire or rod;

[0068] Figure 6 A side view showing an assembly according to the present invention;

[0069] Figures 7a to 7c A schematic view showing the steps in the method according to the present invention;

[0070] Figure 8 A cross-sectional view showing an embodiment of an assembly manufactured according to and by way of an embodiment of the method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0071] Figure 1 A cross-sectional view showing an embodiment of an assembly manufactured according to and by way of an embodiment of the method of the present invention, the assembly including a center pin 20 made of a piece 19 of wire or rod, the piece 19 having a core 21 of a first material along its length, the core 21 being surrounded by an outer layer 22 of a second material (see Figure 2, which shows a cross-sectional view of such a part 19 of a wire or rod), the second material being different from the first material. In this embodiment, the intermediate electrode 6 is welded to the end of the part of the wire or rod, preferably to a shoulder cut into the outer layer 22. A high-energy beam (preferably, a laser beam) is directed onto the exposed core 21, and powder is melted onto the exposed core 21 by the high-energy beam such that after re-solidification of the material of the core 21 and the powder, a microstructure composed of the material of the core 21 and the powder is formed in the contact area 18 between the powder and the exposed core 21, and the core 21 is covered by the re-solidified powder 25 at one end of the part 19 of the wire or rod. In this embodiment, the re-solidified powder 25 also covers the weld 10 present between the intermediate electrode 6 and the outer layer 22.

[0072] Figure 3a and Figure 3b shows an embodiment of a spark plug 1 according to the invention, in which the end of the spark plug 1 facing the combustion chamber when the spark plug 1 is installed in an internal combustion engine is shown in more detail.

[0073] The spark plug includes an ignition device 2 carried out by an intermediate electrode 6 and a ground electrode 7, in which a spark gap 8 exists between the intermediate electrode 6 and the ground electrode 7. The ground electrode 7 is arranged on a ground electrode carrier 9. In this particular embodiment, the wall 3 surrounding the ignition device 2 is formed as part of the spark plug body. The spark plug body surrounds the ground electrode carrier 9, and at least one ground electrode 7 is connected to the ground electrode carrier 9, for example, by laser beam welding.

[0074] The weld 10 preferably has a type such that the part of it is beveled. Thus, in such an embodiment, it may be necessary for the weld 10 to be deep enough so that the ground electrode carrier 9 is properly fixed by the weld 10.

[0075] The manufacturing method may include the step in which a groove for the weld 10 is manufactured to a certain depth such that at least a part of the weld 10 serves as a connection between the ground electrode carrier 9 and the spark plug body, even after the manufacture of the bevel 5.

[0076] The intermediate electrode 6 is connected to the intermediate electrode carrier 13 by laser beam welding. The intermediate electrode carrier 13 (including or consisting of a metal preferably nickel) is arranged at the end of a center pin 20, which is composed of a part 19 of a wire or rod having a core 21 and an outer layer 22, such that the intermediate electrode carrier 13 contacts the core 21. The intermediate electrode carrier 13 and the center pin 20 form a component according to the invention.

[0077] The center pin 20 is arranged within an opening of an insulator 14 made of, for example, ceramic.

[0078] In order to seal the combustion chamber relative to the environment, in this embodiment, the spark plug 1 includes a sealing area 4 which is designed as an inclined surface 5. The inclined surface 5 is disposed at the wall 3 (which is formed by the spark plug body in this embodiment). It should be noted that the central pin 20 according to the present invention can be used for all types of spark plugs 1, and in particular, can also be used for spark plugs 1 that are sealed relative to the environment as taught in the art.

[0079] The spark plug body (wall 3) further includes a mounting portion 11 for mounting the spark plug 1 in an internal combustion engine and / or in a cylinder head and / or in a spark plug sleeve. In this embodiment, the mounting portion 11 is provided as an (external) thread 12.

[0080] Figure 3c An isometric view of a second embodiment showing a similar Figure 3a embodiment. The only difference is that the weld 10 is absent in Figure 3c it.

[0081] In Figure 3c it can be seen that the ground electrode 7 is designed as an annular electrode, where the annular electrode surrounds the central electrode 6 having a circular shape, and an annular spark gap 8 is formed between the ground electrode 7 and the central electrode 6.

[0082] Furthermore, in this embodiment it can be seen that the inclined surface 5 extends to the ground electrode carrier 9, with the advantage of enhancing heat transfer between the spark plug body 3 and the spark plug sleeve and between the ground electrode carrier 9 and the spark plug sleeve.

[0083] The sealing area 4 in the form of the inclined surface 5 is designed at an angle α with respect to the perpendicular y to the central axis x of the spark plug 1. This can be seen in more detail in Figure 3b it. The inclined surface 5 can have an angle α within a wide range (for example, between 20° and 45°) with respect to the perpendicular y to the central axis x of the spark plug 1. When the spark plug 1 is installed in a spark plug sleeve or directly in a cylinder head, the external thread 12 that mates with the internal thread of the spark plug sleeve or cylinder head is configured to preload the inclined surface 5 of the spark plug 1 against the surface of the corresponding spark plug sleeve or cylinder head.

[0084] The spark plug 1 can be substantially symmetric about the central axis x.

[0085] Figure 4A cross-sectional view of a wire or rod suitable for a component according to the present invention is shown. It can be seen in this figure that the wire or rod is formed as a coated wire or coated rod having a core 21, and the core 21 is composed of a material (preferably including copper or a copper alloy or consisting of copper or a copper alloy) having a higher thermal conductivity than the outer layer 22. The core 21 can be composed of any material with high thermal conductivity (such as silver or gold). The outer layer 22 is composed of a material (preferably including nickel or consisting of nickel) having a higher heat and corrosion resistance than the core 21.

[0086] Figure 5a 、 Figure 5b A side view and a cross-sectional view of a component according to the present invention are shown, in which the body has been formed as an intermediate product on a wire or rod. Such a wire or rod can be obtained, for example, from a coil 27, preferably by cutting to a desired length (see Figure 7a ). The first end of the piece of wire or rod can be processed, for example, by turning, milling, grinding or polishing to make it more suitable for subsequent steps.

[0087] It can be provided that the central pin 20 composed of a wire or rod can be manufactured by a drawing process. In this case, a core 21 having an exemplary diameter of, for example, 2 - 3 mm is introduced into an outer layer 22 (for example, a tube having an initial outer diameter of, for example, 5 mm and an inner diameter of 3.8 mm) in a first step. In the next step, the component is processed by a drawing method to obtain a wire or rod having a core 21 and an outer layer 22 according to the present invention. Such a drawing process is well known in the prior art. The resulting wire or rod can have a diameter of, for example, 3.8 mm, but of course all diameters are possible to be produced via such a drawing technique. In the next step, the wire or rod can be processed as described above and below.

[0088] Powder deposition techniques are used to form the body on one end of the piece of wire or rod, that is, the body is manufactured in at least one layer such that for each layer, uncured powder 26 (see Figure 7b ) is deposited on the said one end of the piece of wire and melted - preferably by a high-energy beam (such as a laser beam 24 - see Figure 7b - or an electron beam) - and re-cured into (re) cured powder 25 to form the at least one layer.

[0089] As mentioned, the body serves as an intermediate product of the intermediate electrode carrier 13 and has a larger size relative to at least one direction (preferably relative to the longitudinal axis of the wire or rod).

[0090] In a further manufacturing step for obtaining the intermediate electrode carrier 13 from the intermediate product (reference Figure 7c) In this case, material is removed from the body shown in the figure to obtain a body with reduced dimensions, preferably dimensions corresponding to those of the intermediate electrode carrier 13, and the body has a desired pre-defined distance d between the core 21 of the piece of wire or rod and the mounting surface for the intermediate electrode carrier 13. In Figure 7c the desired dimensions are shown by dashed lines.

[0091] In an embodiment according to Figure 8 , it may be provided that a wire or rod is supplied to the manufacturing process in which, in the region of one end of the wire or rod, at least the outer layer 22 is removed, preferably by turning or milling (it may be provided that a small amount of the core diameter is also removed, for example, by turning or milling). In the next step, a layer having the thickness described above is coated onto the uncoated portion of the core 21 in the region of one end via a powder deposition technique as described above. After this process (which also results in a shoulder in the region of one end of the wire or rod), the intermediate electrode can be attached, for example, via a welding process.

[0092] Independent of the embodiment, due to the fact that the distance between the intermediate electrode carrier 13 (and thus to the intermediate electrode 6) and the core 21 can be appropriately defined, a beneficial result will positively affect heat conduction.

[0093] List of reference signs:

[0094] 1 Spark plug

[0095] 2 Ignition device

[0096] 3 Wall

[0097] 4 Sealing zone

[0098] 5 Bevel

[0099] 6 Intermediate electrode

[0100] 7 Ground electrode

[0101] 8 Spark gap

[0102] 9 Ground electrode carrier

[0103] 10 Weld seam

[0104] 11 Mounting part

[0105] 12 External thread

[0106] 13 Intermediate electrode carrier

[0107] 14 Isolator

[0108] 15 Powder nozzle

[0109] 16 Anti-rotation lock

[0110] 17 Concavity

[0111] 18 Contact area of powder and exposed core

[0112] 19 Piece of wire or rod

[0113] 20 Central pin

[0114] 21 Core

[0115] 22 Outer layer

[0116] 23 Shoulder

[0117] 24 Laser beam

[0118] 25 (Re) cured powder

[0119] 26 (Uncured) powder

[0120] 27 Coil of wire or rod

[0121] 28 Powder nozzle

[0122] d Distance

[0123] x Central axis of the spark plug

[0124] y Perpendicular line y to the central axis of the spark plug

[0125] α Angle relative to the perpendicular line to the central axis of the spark plug.

Claims

1. A method for manufacturing a component of a central pin (20) and a corresponding intermediate electrode carrier (13) or intermediate electrode (6) for a spark plug (1), the spark plug (1) being usable for igniting a combustible air-fuel mixture in an internal combustion engine, characterized in that: - providing a piece (19) of wire or rod, the piece (19) having a core (21) of a first material over its length, the core (21) being surrounded by an outer layer (22) of a second material different from the first material, wherein the core is exposed at one end of the piece of wire or rod, - a corresponding intermediate electrode carrier (13) or intermediate electrode (6) is provided at the one end of the piece (19) of wire or rod, - a high-energy beam is directed to the exposed core (21), and powder is melted onto the exposed core (21) by the high-energy beam such that after re-solidification of the material of the core (21) and the powder, a microstructure composed of the material of the core (21) and the powder is formed in the contact area (18) between the powder and the exposed core (21), and the core (21) is covered by re-solidified powder (25) at the one end of the piece of wire or rod, wherein, after re-solidification, powder is provided to cover a welding node for welding the corresponding intermediate electrode carrier (13) or the intermediate electrode (6) to the outer layer (22).

2. The method according to claim 1, wherein, Before the powder is melted onto the exposed core (21), the corresponding intermediate electrode carrier (13) or the intermediate electrode (6) is welded to the outer layer (22) by forming the welding node.

3. The method according to claim 1, wherein, Before the powder is melted onto the exposed core (21), material is removed from the exposed core (21) to form a pit (30), which is filled with melted powder.

4. The method according to claim 1, wherein, The step of providing the intermediate electrode carrier (13) or the intermediate electrode (6) at the one end of the piece (19) of wire or rod includes the step of attaching or forming a body on the one end of the piece (19) of wire or rod, the body - either forming the corresponding intermediate electrode carrier (13) or the intermediate electrode (6), or - serving as an intermediate product for the corresponding intermediate electrode carrier (13) or the intermediate electrode (6), wherein the intermediate electrode carrier (13) or the intermediate electrode (6) is obtained from the intermediate product by at least one additional manufacturing step.

5. The method according to claim 4, wherein The body serves as an intermediate product for the corresponding intermediate electrode carrier (13) or the intermediate electrode (6) and has a larger size relative to at least one direction, and wherein the additional manufacturing step for obtaining the corresponding intermediate electrode carrier (13) or the intermediate electrode (6) from the intermediate product includes at least one step in which material is removed from the body to obtain a body with a reduced size.

6. The method according to claim 5, wherein The body has the larger size relative to the longitudinal axis of the wire or the rod.

7. The method according to claim 5, wherein The reduced size corresponds to the size of the respective intermediate electrode carrier (13) or the intermediate electrode (6).

8. The method according to claim 4, wherein The additional manufacturing steps for obtaining the intermediate electrode carrier (13) from the intermediate product include at least one step in which a shoulder (23) is formed on the body.

9. The method according to any one of claims 4 to 8, wherein, The body forms the respective intermediate electrode carrier (13) or the intermediate electrode (6) and is welded to one end of the piece (19) of the wire or rod, the body having a shoulder (23) or being placed on a shoulder (23) already formed in one end of the piece (19) of the wire or rod.

10. The method according to claim 4, wherein, The mounting surface of the respective intermediate electrode carrier (13) or the intermediate electrode (6) for the intermediate electrode has a predefined distance (d) to the core (21) relative to the longitudinal axis of the wire or the rod.

11. The method according to claim 10, wherein, The predefined distance (d) from the mounting surface of the intermediate electrode carrier (13) to the core (21) is obtained by using a body that has at least a larger size relative to the longitudinal axis of the wire or the rod, and the material of the body is removed in a direction parallel to the longitudinal axis of the wire or the rod such that the predefined distance (d) is formed.

12. The method according to claim 1, wherein, A piece (19) of wire or rod is used, where the core (21) consists of a material having a higher thermal conductivity than the outer layer (22), and the core (21) comprises copper or consists of copper.

13. The method according to claim 1, wherein, A piece (19) of wire or rod is used, where the outer layer (22) consists of a material having a higher heat corrosion resistance than the core (21), and the outer layer (22) comprises nickel or consists of nickel.

14. The method according to claim 1, wherein, The intermediate electrode carrier (13) comprises metal or consists of the metal, and / or where the intermediate electrode (6) comprises a noble metal or consists of a noble metal.

15. A method for manufacturing a spark plug (1) that can be used to ignite a combustible air-fuel mixture in an internal combustion engine, characterized in that, The method according to any one of claims 1 - 14 is used for manufacturing an assembly of the central pin (20) and the intermediate electrode carrier (13) of the spark plug (1).

16. An assembly of a central pin (20) and a respective intermediate electrode carrier (13) or intermediate electrode (6) for a spark plug (1), the spark plug (1) being capable of being used for igniting a combustible air - fuel mixture in an internal combustion engine, characterized in that - the central pin (20) comprises a piece (19) of wire or rod, which has a core (21) of a first material along its length, the core (21) being surrounded by an outer layer (22) of a second material, the second material being different from the first material, - the respective intermediate electrode carrier (13) or the intermediate electrode (6) is attached to one end of the piece of wire or rod, - the end of the core (21) of the central pin (20) is covered by a material provided in the form of a molten powder, and the material is re - solidified such that in the contact area (18) between the re - solidified powder (25) and the core (21) there is a microstructure consisting of the material of the core (21) and the powder; Among them, the welding nodes for welding the corresponding intermediate electrode carrier (13) or the intermediate electrode (6) to the outer layer (22) are covered by the re-solidified powder (25).

17. The component according to claim 16, wherein, An anti-rotation lock (16) is provided at one end of the central pin (20).

18. A spark plug (1) capable of igniting a combustible fuel in an internal combustion engine, characterized in that, The spark plug (1) includes the assembly according to any one of claims 16 to 17.

19. The spark plug according to claim 18, further comprising: - An ignition device (2), which is arranged at the end of the spark plug (1) facing the combustion chamber when the spark plug (1) is installed in the internal combustion engine, and the ignition device (2) includes the intermediate electrode (6) and the ground electrode (7), - A wall (3), which at least partially surrounds the ignition device (2), and - A sealing zone (4), which is used to seal the combustion chamber relative to the environment, wherein the wall (3) includes the sealing zone (4) at the end of the wall (3), and when the spark plug (1) is installed in the internal combustion engine, the end faces the combustion chamber. Among them, the sealing zone (4) is the end portion of the wall (3), and when the spark plug (1) is installed in the internal combustion engine, the end portion faces the combustion chamber, and the sealing zone (4) is designed as an inclined surface (5).

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