EP3235079B1 - Spark plugs with central electrode - Google Patents

Spark plugs with central electrode Download PDF

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Publication number
EP3235079B1
EP3235079B1 EP15804147.5A EP15804147A EP3235079B1 EP 3235079 B1 EP3235079 B1 EP 3235079B1 EP 15804147 A EP15804147 A EP 15804147A EP 3235079 B1 EP3235079 B1 EP 3235079B1
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EP
European Patent Office
Prior art keywords
electrode
main body
region
core
spark plug
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Application number
EP15804147.5A
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German (de)
French (fr)
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EP3235079A1 (en
Inventor
Manfred Roeckelein
Andreas Benz
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Robert Bosch GmbH
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Robert Bosch GmbH
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Publication of EP3235079A1 publication Critical patent/EP3235079A1/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
    • H01T13/39—Selection of materials for electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/02—Details
    • H01T13/16—Means for dissipating heat
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
    • H01T13/32—Sparking plugs characterised by features of the electrodes or insulation characterised by features of the earthed electrode

Definitions

  • the invention is based on a spark plug according to the preamble of the independent claim.
  • the DE 10 2004 044 152 A1 discloses a spark plug according to the preamble of claim 1.
  • the insulator is the more sensitive component in the spark plug in terms of mechanical and electrical loads than the metallic components.
  • the object of the present invention is to provide a spark plug which can meet the requirements mentioned at the beginning.
  • the electrode base body has three areas, of which a third area has a constant diameter that corresponds to a diameter of a second area at the transition to the third area, it is achieved according to the invention that a spark plug with this central electrode meets the above-mentioned requirements.
  • the insulator can be made with a sufficient wall thickness, so that the spark plug can withstand the thermal, mechanical and electrical loads during operation.
  • the center electrode or the electrode base body have areas of different diameters.
  • the stated limits for the diameter of the electrode main body relate in each case to the largest diameter of the electrode main body, neglecting the electrode head.
  • the electrode head is formed on the end of the center electrode facing away from the combustion chamber. In the case of the spark plug, the electrode head rests on a seat formed on the inside of the insulator. The electrode head extends from the seat formed on the inside of the insulator to the end of the center electrode facing away from the combustion chamber. If the geometry of the cross section of the electrode base body deviates from the round shape, then the diameter relates to the circumference of the non-round geometry of the cross section of the electrode base body.
  • the diameter of the electrode base body is not greater than 1.5 mm.
  • the diameter of the electrode base body is not smaller than 1 mm so that the stability of the center electrode itself is not endangered.
  • the electrode base body should preferably have this minimum diameter so that the cross-section of the electrode base body is large enough for sufficient heat dissipation along the center electrode, so that the insulator at its end on the combustion chamber side does not additionally burden the heat absorbed from the combustion chamber with the heat absorbed by the central electrode becomes.
  • the heat absorbed by the combustion chamber is conducted within the center electrode to areas further away from the combustion chamber and therefore cooler.
  • the housing and the center electrode are at different electrical potentials.
  • the center electrode and the housing have their smallest distance from one another due to the design. This makes this area of the insulator very susceptible to electrical breakdowns.
  • the insulator it has been found to be advantageous for the insulator to have a wall thickness of not less than 2 mm in the area of the seat formed on its inside. Additionally or alternatively, it can be provided that the area of the insulator surrounding the electrode head has a wall thickness of not less than 2 mm. It is thereby achieved that the insulator has a sufficiently large wall thickness to withstand the high electrical fields occurring in the area of the seat formed on the insulator and the electrical breakdowns caused thereby.
  • the core of the electrode base body consists of a material which has a higher thermal conductivity than the material of the electrode base body. This promotes heat conduction within the basic electrode body.
  • the material of the core preferably has a thermal conductivity of at least 350 W / mK at room temperature. Additionally or alternatively, it can be provided that at room temperature the thermal conductivity of the material of the core is at least 300 W / mK greater than the thermal conductivity of the material of the electrode base body.
  • the electrode base body has, for example, an alloy containing nickel.
  • the alloy preferably contains at least 20% by weight of chromium, in particular at least 25% by weight of chromium.
  • this alternatively or additionally contains yttrium.
  • the core consists for example of copper or silver or an alloy with copper and / or silver. Investigations by the applicant have shown that, for example, a copper-containing core in the electrode base body reduces the temperature at the end of the electrode base body facing the combustion chamber by 50-80K.
  • the cross-sectional area of the core is not less than 20% of the cross-sectional area of the electrode base body or the center electrode in at least one first area, with at least one first area Area of the electrode base body and the core each have a constant diameter.
  • the cross-sectional area of the electrode base body is composed of the cross-sectional area of the core and the cross-sectional area of the jacket.
  • the at least one first area is preferably cylindrical.
  • the at least one first area preferably has a length along the longitudinal axis of the center electrode that is equal to or longer than the diameter of the electrode base body in this first area, in particular the length of the at least one first area is at least 1.5 times as long as Diameter of the electrode body.
  • the cross-sectional area of the core corresponds to a maximum of 65% of the total cross-sectional area of the electrode base body or the center electrode. This ensures that the center electrode has a sufficiently large jacket thickness.
  • the electrode base body is advantageously made of a more wear-resistant material than the core, so that the electrode base body preferably has to have a minimum jacket thickness so that the center electrode has a sufficiently long service life, for example at least 50,000 km.
  • the electrode base body has a minimum jacket thickness of not less than 0.15 mm, in particular not less than 0.25 mm. Additionally or alternatively, it can be provided that the jacket thickness in the at least one first region with constant diameters of the core and the electrode base body is not greater than 0.35 mm.
  • the center electrode has an ignition surface containing noble metal on its end surface on the combustion chamber side, which ignition surface has a higher wear resistance than the material of the electrode base body.
  • the distance b from the ignition surface to the core has a value in the range from 0.2 mm to 2 mm.
  • the center electrode has no ignition surface.
  • the distance b from the end face of the electrode base body on the combustion chamber side to the end of the core on the combustion chamber side is at least 0.6 mm long in order to ensure a sufficiently long service life of the center electrode.
  • the distance b preferably has a value which is not smaller than 1 mm, and in particular is not larger than 3.5 mm.
  • the cross-sectional area of the core and the cross-sectional area of the electrode base body have the same geometric shape, in particular the core being arranged within a cross-sectional plane in the center of the electrode base body. This ensures that the electrode base body has a uniform jacket thickness within the cross-sectional plane.
  • Spark plugs with a reduced outer diameter of the housing are, in the context of this application, spark plugs whose threads have an outer diameter smaller than 14 mm, for example so-called M12 or M10 spark plugs.
  • FIG. 1 shows schematic representations of the center electrode 10.
  • the center electrode 10 has an electrode base body 11 and a core 12, which is arranged within the electrode base body 12.
  • the core 11 consists of a material with a higher thermal conductivity than the material of the electrode base body 11.
  • the material of the electrode base body 11 has a higher wear resistance than the material of the core 12.
  • the core 12 consists of copper, silver or an alloy with copper and / or silver.
  • a Ni alloy is preferably used as the material for the electrode base body 11, and the alloy can contain chromium and / or yttrium.
  • the core of the center electrode 10 shown here in section has at least one first section 15a in which the core 12 has a relatively constant diameter d K.
  • the term “relatively constant” means that the diameter d K in the section changes its value by a maximum of 5%.
  • the diameter d K of the core 12 is reduced within a second section 14a.
  • the at least one first section 15a is arranged on a side of the center electrode 10 facing away from the combustion chamber, with an electrode head 4 (not shown here) following the end of the first facing away from the combustion chamber Section 15 is formed.
  • the second section 14a adjoins the at least one first section 15a.
  • the core 12 has a plurality of first sections 15a with constant diameters d K , the diameters d K of the individual first sections 15a being different. This is particularly the case when the center electrode 10 or the electrode base body 11 itself has a plurality of regions with different diameters d E.
  • the section closest to the combustion chamber is the second section 14a with the continuously decreasing diameter d K of the core 12.
  • the center electrode 10 shown is constructed from an electrode base body 11 which has a constant diameter d E along its length and thus the center electrode 10 also has a constant diameter d E.
  • the electrode base body 11 In the case of the electrode base body 11, at least three areas 13, 14, 15 can be distinguished. In a first region 15, the electrode base body 11 has a core 12 with a constant diameter d K. In a second region 14a, the electrode base body 11 has a core 12 with a continuously reducing diameter d K. In a third region 13, the electrode base body 11 does not have a core.
  • the thickness c of the jacket of the electrode base body 11 results from half the difference between the electrode base body diameter d E and the core diameter d K. If the electrode base body 11 has a constant diameter d E1 in the first region 15, then the jacket thickness c in this first region 15 is constant. It is advantageously provided that in this first region 15 the jacket thickness c of the electrode base body 11 is not less than 0.15 mm and not greater than 0.35 mm, for example the jacket thickness c is 0.25 mm or less.
  • the electrode base body 11 can have a constant diameter d E2 , in which case the jacket thickness c increases within the region 14 in the direction of the combustion chamber.
  • the jacket thickness c is at least 0.15 mm thick in the region 14.
  • the diameter d E2 of the electrode base body 11 is also reduced in the second region 14.
  • the jacket thickness c it is preferably in the range from 0.15 mm to 0.35 mm. It can be provided that the diameter d E2 of the electrode base body 11 changes at the same rate as the diameter d K of the core 12. This has the advantage that the jacket thickness c remains constant in the second region 14.
  • the jacket thickness c corresponds to half the diameter d E3 of the electrode base body 11.
  • the third area 13 has a constant diameter d E3 , which corresponds to the diameter d E2 of the second area 14 at the transition to third area 13 corresponds.
  • the third region 13 of the electrode base body 11 has a length b which extends from an end 17 of the core 12 on the combustion chamber side to an end face 16 of the electrode base body 11 on the combustion chamber side.
  • the length b is not greater than 3.5 mm. If the center electrode 10 is designed with a noble metal-containing ignition surface 19, the length b can be made shorter than without a noble metal-containing ignition surface 19, as in FIG Figure 1b shown. If a noble metal-containing ignition surface 19 is dispensed with, as in Figure 1a shown, then the length b should have a minimum length of 0.6 mm so that the noble metal base body 12 has enough material for a sufficiently long service life of the center electrode 10. When using a noble metal-containing ignition surface 19, a length b of at least 0.2 mm is sufficient for a sufficiently long service life of the center electrode 10.
  • Figure 2 shows an example of a cross section of the center electrode 10.
  • the diameter d E of the center electrode 10 and the electrode base body 11 is less than 1.7 mm.
  • the cross section of the core 12 is arranged centrally in the cross section of the center electrode 10 or of the electrode base body 11.
  • the thickness c of the jacket of the electrode base body 11 results from half the difference between the electrode base body diameter d E and the core diameter d K.
  • the cross-sections of the electrode base body 11 and of the core 12 advantageously have the same geometric shape.
  • FIG. 3 shows a schematic representation of a spark plug 1 with a central electrode 10 according to the invention.
  • the spark plug 1 has a metallic housing 2 with a thread for mounting the spark plug 1 in a cylinder head. Furthermore, the housing has a hexagon section 9, on which a tool for mounting the spark plug 1 in the cylinder head is attached.
  • An insulator 3 is arranged inside the housing 2.
  • a center electrode 10 and a connecting bolt 7 are arranged inside the insulator 3 and are electrically connected via a resistance element 6.
  • the insulator (3) On the inside of the insulator 3 there is a seat (3a) on which the center electrode (10) rests with its center electrode head (4).
  • the insulator (3) has a wall thickness of not less than 2 mm in the area of the seat (3a).
  • the center electrode 10 typically protrudes from the insulator 3 at the end of the spark plug 1 on the combustion chamber side.
  • the center electrode has a base body 10 and an ignition surface 19 arranged on the end of the base body on the combustion chamber side.
  • the base body 10 has a core 12 which is surrounded by a jacket 11.
  • a ground electrode 5 is arranged at the end of the housing 2 on the combustion chamber side. Which forms an ignition gap together with the center electrode 10.
  • the ground electrode 5 can be designed as a roof electrode, side electrode or bracket electrode.

Description

Stand der TechnikState of the art

Die Erfindung geht von einer Zündkerze nach dem Oberbegriff des unabhängigen Anspruchs aus.The invention is based on a spark plug according to the preamble of the independent claim.

Aufgrund der zunehmenden Reduzierung des Bauraums im Motorraum stehen für die einzelnen Komponenten, wie beispielsweise die Zündkerze, im Motorraum weniger Platz zur Verfügung und die Komponenten im Motorraum müssen verkleinert werden. Durch den Trend des sogenannten Downsizings der Komponenten treten neue Herausforderungen bei der Konstruktion der Komponenten und der Zündkerze auf.Due to the increasing reduction in installation space in the engine compartment, there is less space available in the engine compartment for the individual components, such as the spark plug, and the components in the engine compartment must be made smaller. The trend of so-called downsizing of the components creates new challenges in the design of the components and the spark plug.

Durch das Downsizing der Zündkerze und ihrer Komponenten steigt die thermische, elektrische und mechanische Belastung an der Zündkerze und ihren einzelnen Komponenten. Gleichzeitig soll die Zündkerze eine gleich gute Zünd-Zuverlässigkeit und eine gleich lange Lebensdauer wie bisherige nicht dem Downsizing unterworfene Zündkerzen aufweisen.Downsizing the spark plug and its components increases the thermal, electrical and mechanical stress on the spark plug and its individual components. At the same time, the spark plug should have the same good ignition reliability and the same long service life as previous spark plugs that were not subject to downsizing.

Die DE 10 2004 044 152 A1 offenbart eine Zündkerze gemäß dem Oberbegriff des Anspruchs 1.The DE 10 2004 044 152 A1 discloses a spark plug according to the preamble of claim 1.

Offenbarung der ErfindungDisclosure of the invention

Eine Anpassung des Isolators und der Mittelelektrode an die durch das Downsizing entstehenden neuen Anforderungen ist eine Herausforderung. Der Isolator ist aufgrund seiner keramischen Natur im Vergleich zu den metallischen Komponenten im Bezug auf mechanische und elektrische Belastungen die empfindlichere Komponente in der Zündkerze.Adapting the insulator and the center electrode to the new requirements resulting from the downsizing is a challenge. Due to its ceramic nature, the insulator is the more sensitive component in the spark plug in terms of mechanical and electrical loads than the metallic components.

Untersuchungen der Anmelderin haben gezeigt, dass bei Zündkerzen mit ein Gehäuse, einen im Gehäuse angeordneten Isolator, eine im Isolator angeordnete Mittelelektrode und eine am Gehäuse angeordnete Masseelektrode, wobei die Masseelektrode und die Mittelelektrode so zueinander angeordnet sind, dass die Masseelektrode und die Mittelelektrode einen Zündspalt ausbilden, und wobei die Mittelelektrode mit einem Elektrodenkopf auf einen auf einer Innenseite des Isolators ausgebildeten Sitz aufliegt, und wobei die Mittelelektrode einen Elektrodengrundkörper und einen im Elektrodengrundkörper angeordneten Kern aufweist, wobei der Kern aus einem Material besteht, das eine höhere Wärmeleitfähigkeit als das Material des Elektrodengrundkörpers hat, zur Gewährleistung der mechanischen und elektrischen Stabilität des Isolators eine minimale Wandstärke nicht unterschritten werden sollte. Es gilt ein Optimum zwischen der Stabilität und Wärmeableitung des Isolators einerseits und der Wärmeableitung der Zündkerze insgesamt sowie der Lebensdauer der Zündkerze andererseits zu erzielen.Investigations by the applicant have shown that in spark plugs with a housing, an insulator arranged in the housing, a center electrode arranged in the insulator and a ground electrode arranged on the housing, the ground electrode and the center electrode being arranged with respect to one another in such a way that the ground electrode and the center electrode form an ignition gap form, and wherein the center electrode with a The electrode head rests on a seat formed on an inside of the insulator, and the center electrode has an electrode base body and a core arranged in the electrode base body, the core being made of a material that has a higher thermal conductivity than the material of the electrode base body to ensure the mechanical and electrical stability of the insulator should not fall below a minimum wall thickness. The aim is to achieve an optimum between the stability and heat dissipation of the insulator on the one hand and the heat dissipation of the spark plug as a whole and the service life of the spark plug on the other hand.

Die Aufgabe der vorliegenden Erfindung ist es, eine Zündkerze bereit zu stellen, die die eingangs genannten Anforderungen erfüllen kann.The object of the present invention is to provide a spark plug which can meet the requirements mentioned at the beginning.

Diese Aufgabe wird von der erfindungsgemäßen Zündkerze durch den kennzeichnenden Teil des Anspruchs 1 gelöst.This object is achieved by the spark plug according to the invention by the characterizing part of claim 1.

Dadurch, dass der Elektrodengrundkörper drei Bereiche aufweist, von welchen ein dritter Bereich einen konstanten Durchmesser aufweist, der einem Durchmesser eines zweiten Bereichs beim Übergang zum dritten Bereich entspricht, wird erfindungsgemäß erreicht, dass eine Zündkerze mit dieser Mittelelektrode die oben genannten Anforderungen erfüllt. Der Isolator kann mit einer ausreichende Wandstärke ausbildet werden, wodurch die Zündkerze den thermischen, mechanischen und elektrischen Belastungen beim Betrieb standhält.Because the electrode base body has three areas, of which a third area has a constant diameter that corresponds to a diameter of a second area at the transition to the third area, it is achieved according to the invention that a spark plug with this central electrode meets the above-mentioned requirements. The insulator can be made with a sufficient wall thickness, so that the spark plug can withstand the thermal, mechanical and electrical loads during operation.

Die Mittelelektrode bzw. der Elektrodengrundkörper weisen Bereiche unterschiedlicher Durchmesser auf. Die genannten Grenzen für den Durchmesser des Elektrodengrundkörpers beziehen sich jeweils auf den größten Durchmesser des Elektrodengrundkörpers unter Vernachlässigung des Elektrodenkopfes. Der Elektrodenkopf ist an dem Brennraum-abgewandten Ende der Mittelelektrode ausgebildet. Bei der Zündkerze liegt der Elektrodenkopf auf einen auf der Innenseite des Isolators ausgebildeten Sitz auf. Der Elektrodenkopf erstreckt sich von dem auf der Isolator-Innenseite ausgebildeten Sitz bis zum Brennraum-abgewandten Ende der Mittelelektrode. Wenn die Geometrie des Querschnitts des Elektrodengrundkörpers von der runden Form abweicht, dann bezieht sich der Durchmesser auf den Umkreis der nicht runden Geometrie des Querschnitts des Elektrodengrundkörpers.The center electrode or the electrode base body have areas of different diameters. The stated limits for the diameter of the electrode main body relate in each case to the largest diameter of the electrode main body, neglecting the electrode head. The electrode head is formed on the end of the center electrode facing away from the combustion chamber. In the case of the spark plug, the electrode head rests on a seat formed on the inside of the insulator. The electrode head extends from the seat formed on the inside of the insulator to the end of the center electrode facing away from the combustion chamber. If the geometry of the cross section of the electrode base body deviates from the round shape, then the diameter relates to the circumference of the non-round geometry of the cross section of the electrode base body.

Bei einer bevorzugten Weiterbildung ist der Durchmesser des Elektrodengrundkörpers nicht größer als 1,5 mm.In a preferred development, the diameter of the electrode base body is not greater than 1.5 mm.

Weitere vorteilhafte Ausgestaltungen sind Gegenstand der Unteransprüche.Further advantageous configurations are the subject of the subclaims.

Alternativ oder zusätzlich kann auch vorgesehen sein, dass der Durchmesser des Elektrodengrundkörpers nicht kleiner als 1 mm ist, damit die Stabilität der Mittelelektrode selbst nicht gefährdet wird. Vorzugsweise sollte der Elektrodengrundkörper diesen Mindestdurchmesser aufweisen, damit der Querschnitt des Elektrodengrundkörpers groß genug ist für eine ausreichende Wärmeableitung entlang der Mittelelektrode, so dass der Isolator an seinem brennraumseitigen Ende neben der aus dem Brennraum aufgenommene Wärme nicht zusätzlich noch mit der von der Mittelelektrode aufgenommene Wärme belastet wird. Idealerweise wird die vom Brennraum aufgenommene Wärme innerhalb der Mittelelektrode in vom Brennraum weiter entfernte und damit kühlere Bereiche geleitet.Alternatively or additionally, it can also be provided that the diameter of the electrode base body is not smaller than 1 mm so that the stability of the center electrode itself is not endangered. The electrode base body should preferably have this minimum diameter so that the cross-section of the electrode base body is large enough for sufficient heat dissipation along the center electrode, so that the insulator at its end on the combustion chamber side does not additionally burden the heat absorbed from the combustion chamber with the heat absorbed by the central electrode becomes. Ideally, the heat absorbed by the combustion chamber is conducted within the center electrode to areas further away from the combustion chamber and therefore cooler.

Das Gehäuse und die Mittelelektrode liegen auf unterschiedlichen elektrischen Potentialen. Im Bereich des am Isolator ausgebildeten Sitzes haben die Mittelelektrode und das Gehäuse konstruktionsbedingt ihren geringsten Abstand zueinander. Dadurch ist dieser Bereich des Isolators sehr anfällig für elektrische Durchschläge. Zur Verhinderung dieser elektrischen Durchschläge am Isolator hat es sich als vorteilhaft herausgestellt, dass der Isolator im Bereich des auf seiner Innenseite ausgebildeten Sitzes eine Wandstärke von nicht kleiner als 2 mm aufweist. Zusätzlich oder alternativ kann vorgesehen sein, dass der den Elektrodenkopf umgebenden Bereich des Isolator eine Wandstärke von nicht kleiner als 2 mm aufweist. Dadurch wird erreicht, dass der Isolator eine ausreichend große Wandstärke aufweist, um die im Bereich des am Isolator ausgebildeten Sitzes auftretenden hohen elektrischen Felder und dadurch verursachte elektrische Durchschläge standzuhalten.The housing and the center electrode are at different electrical potentials. In the area of the seat formed on the insulator, the center electrode and the housing have their smallest distance from one another due to the design. This makes this area of the insulator very susceptible to electrical breakdowns. To prevent these electrical breakdowns on the insulator, it has been found to be advantageous for the insulator to have a wall thickness of not less than 2 mm in the area of the seat formed on its inside. Additionally or alternatively, it can be provided that the area of the insulator surrounding the electrode head has a wall thickness of not less than 2 mm. It is thereby achieved that the insulator has a sufficiently large wall thickness to withstand the high electrical fields occurring in the area of the seat formed on the insulator and the electrical breakdowns caused thereby.

Erfindungsgemäß besteht der Kern des Elektrodengrundkörpers aus einem Material, das eine höhere Wärmeleitfähigkeit als das Material des Elektrodengrundkörpers aufweist. Dadurch wird die Wärmeleitung innerhalb des Elektrodengrundkörpers begünstigt. Das Material des Kerns weist vorzugsweise eine Wärmeleitfähigkeit von mindestens 350 W/mK bei Raumtemperatur auf. Zusätzlich oder alternativ kann vorgesehen sein, dass bei Raumtemperatur die Wärmeleitfähigkeit des Materials des Kerns mindestens 300 W/mK größer ist als die Wärmeleitfähigkeit des Materials des Elektrodengrundkörpers.According to the invention, the core of the electrode base body consists of a material which has a higher thermal conductivity than the material of the electrode base body. This promotes heat conduction within the basic electrode body. The material of the core preferably has a thermal conductivity of at least 350 W / mK at room temperature. Additionally or alternatively, it can be provided that at room temperature the thermal conductivity of the material of the core is at least 300 W / mK greater than the thermal conductivity of the material of the electrode base body.

Der Elektrodengrundkörper weist beispielsweise eine Nickel-haltige Legierung auf. Vorzugsweise enthält die Legierung mindestens 20 Gew.% Chrom, insbesondere mindestens 25 Gew.% Chrom. Bei einer alternativen Nickel-Legierung enthält diese alternativ oder zusätzlich Yttrium. Der Kern besteht beispielsweise aus Kupfer oder Silber oder einer Legierung mit Kupfer und/oder Silber. Untersuchungen der Anmelderin ergaben, dass beispielsweise ein Kupfer-haltiger Kern im Elektrodengrundkörper die Temperatur an dem Brennraum zugewandten Ende des Elektrodengrundkörpers um 50-80K reduziert.The electrode base body has, for example, an alloy containing nickel. The alloy preferably contains at least 20% by weight of chromium, in particular at least 25% by weight of chromium. In the case of an alternative nickel alloy, this alternatively or additionally contains yttrium. The core consists for example of copper or silver or an alloy with copper and / or silver. Investigations by the applicant have shown that, for example, a copper-containing core in the electrode base body reduces the temperature at the end of the electrode base body facing the combustion chamber by 50-80K.

Weiterführende Untersuchungen der Anmelderin ergaben, dass für eine ausreichend gute Wärmeableitung, d.h. eine Wärmereduzierung innerhalb der Mittelelektrode, die Querschnittsfläche des Kerns nicht kleiner als 20% der Querschnittsfläche des Elektrodengrundkörpers bzw. der Mittelelektrode in mindestens einem ersten Bereich beträgt, wobei in dem mindestens einem ersten Bereich der Elektrodengrundkörper und der Kern jeweils einen konstanten Durchmesser aufweisen. Die Querschnittsfläche des Elektrodengrundkörpers setzt sich zusammen aus der Querschnittsfläche des Kerns und der Querschnittsfläche des Mantels.Further investigations by the applicant showed that for a sufficiently good heat dissipation, ie a heat reduction within the center electrode, the cross-sectional area of the core is not less than 20% of the cross-sectional area of the electrode base body or the center electrode in at least one first area, with at least one first area Area of the electrode base body and the core each have a constant diameter. The cross-sectional area of the electrode base body is composed of the cross-sectional area of the core and the cross-sectional area of the jacket.

Vorzugsweise ist der mindestens eine erste Bereich zylinderförmig. Der mindestens eine erste Bereich weist vorzugsweise ein Länge entlang der Längsachse der Mittelelektrode auf, die gleich oder länger als der Durchmesser des Elektrodengrundkörper in diesem ersten Bereich ist, insbesondere ist die Länge des mindestens einen ersten Bereichs mindestens 1,5-fache so lang wie der Durchmesser des Elektrodengrundkörpers.The at least one first area is preferably cylindrical. The at least one first area preferably has a length along the longitudinal axis of the center electrode that is equal to or longer than the diameter of the electrode base body in this first area, in particular the length of the at least one first area is at least 1.5 times as long as Diameter of the electrode body.

Zusätzlich oder alternativ kann vorgesehen sein, dass die Querschnittsfläche des Kerns maximal 65% der gesamten Querschnittsfläche des Elektrodengrundkörpers bzw. der Mittelelektrode entspricht. Dadurch wird gewährleistet, dass die Mittelelektrode eine ausreichend große Manteldicke aufweist.Additionally or alternatively, it can be provided that the cross-sectional area of the core corresponds to a maximum of 65% of the total cross-sectional area of the electrode base body or the center electrode. This ensures that the center electrode has a sufficiently large jacket thickness.

Vorteilhafterweise besteht der Elektrodengrundkörper aus einem verschleißbeständigeren Material als der Kern, so dass bevorzugterweise der Elektrodengrundkörper eine minimale Manteldicke aufweisen muss, damit die Mittelelektrode eine ausreichende lange Lebensdauer, beispielsweise mindestens 50 000 km, aufweist.The electrode base body is advantageously made of a more wear-resistant material than the core, so that the electrode base body preferably has to have a minimum jacket thickness so that the center electrode has a sufficiently long service life, for example at least 50,000 km.

Es hat sich als vorteilhaft herausgestellt, wenn der Elektrodengrundkörper eine minimale Manteldicke von nicht kleiner als 0,15 mm aufweist, insbesondere nicht kleiner als 0,25 mm. Zusätzlich oder alternativ kann vorgesehen sein, dass die Manteldicke in dem mindestens einen ersten Bereich mit konstanten Durchmessern von dem Kern und dem Elektrodengrundkörper nicht größer ist als 0,35 mm.It has been found to be advantageous if the electrode base body has a minimum jacket thickness of not less than 0.15 mm, in particular not less than 0.25 mm. Additionally or alternatively, it can be provided that the jacket thickness in the at least one first region with constant diameters of the core and the electrode base body is not greater than 0.35 mm.

Bei einer bevorzugten Weiterbildung der Erfindung weist die Mittelelektrode an ihrer brennraumseitigen Stirnfläche eine edelmetallhaltige Zündfläche auf, die eine höhere Verschleißbeständigkeit als das Elektrodengrundkörper-Material hat. Der Abstand b von der Zündfläche bis zum Kern hat einen Wert im Bereich von 0,2 mm bis 2 mm.In a preferred development of the invention, the center electrode has an ignition surface containing noble metal on its end surface on the combustion chamber side, which ignition surface has a higher wear resistance than the material of the electrode base body. The distance b from the ignition surface to the core has a value in the range from 0.2 mm to 2 mm.

Bei einer alternativen Weiterbildung der Erfindung weist die Mittelelektrode keine Zündfläche auf. In diesem Fall ist der Abstand b von der brennraumseitigen Stirnfläche des Elektrodengrundkörpers zum brennraumseitigen Ende des Kerns mindestens 0,6 mm lang, um eine ausreichend lange Lebensdauer der Mittelelektrode zu gewährleisten. Der Abstand b hat vorzugsweise einen Wert der nicht kleiner ist als 1 mm, und insbesondere nicht größer ist als 3,5 mm.In an alternative development of the invention, the center electrode has no ignition surface. In this case, the distance b from the end face of the electrode base body on the combustion chamber side to the end of the core on the combustion chamber side is at least 0.6 mm long in order to ensure a sufficiently long service life of the center electrode. The distance b preferably has a value which is not smaller than 1 mm, and in particular is not larger than 3.5 mm.

Vorteilhaft ist vorgesehen, dass die Querschnittsfläche des Kerns und die Querschnittsfläche des Elektrodengrundkörpers die gleich geometrische Form aufweisen, wobei insbesondere der Kern innerhalb einer Querschnittsebene mittig im Elektrodengrundkörper angeordnet ist. Dadurch wird erreicht, dass der Elektrodengrundkörper innerhalb der Querschnittsebene eine gleichmäßige Mantelstärke aufweist.It is advantageously provided that the cross-sectional area of the core and the cross-sectional area of the electrode base body have the same geometric shape, in particular the core being arranged within a cross-sectional plane in the center of the electrode base body. This ensures that the electrode base body has a uniform jacket thickness within the cross-sectional plane.

Zündkerze mit einem reduzierten Außendurchmesser des Gehäuses sind im Sinne dieser Anmeldung Zündkerzen deren Gewinde einen kleineren Außendurchmesser als 14 mm aufweisen, beispielsweise sogenannte M12- oder M10- Zündkerzen.Spark plugs with a reduced outer diameter of the housing are, in the context of this application, spark plugs whose threads have an outer diameter smaller than 14 mm, for example so-called M12 or M10 spark plugs.

Zeichnungdrawing

  • Figur 1 zeigt zwei Mittelelektroden Figure 1 shows two center electrodes
  • Figur 2 zeigt einen Schnitt der Mittelelektrode Figure 2 Fig. 3 shows a section of the center electrode
  • Figur 3 zeigt eine Zündkerze mit einer Mittelelektrode Beschreibung des Ausführungsbeispiels Figure 3 shows a spark plug with a center electrode describing the embodiment

Figur 1 zeigt schematische Darstellungen der Mittelelektrode 10. Die Mittelelektrode 10 weist einen Elektrodengrundkörper 11 und einen Kern 12 auf, der innerhalb des Elektrodengrundkörpers 12 angeordnet ist. Der Kern 11 besteht aus einem Material mit einer höheren Wärmeleitfähigkeit als das Material des Elektrodengrundkörpers 11. Typischerweise hat das Material des Elektrodengrundkörpers 11 eine höhere Verschleißbeständigkeit als das Material des Kerns 12. Der Kern 12 besteht aus Kupfer, Silber oder einer Legierung mit Kupfer und/oder Silber. Als Material für den Elektrodengrundkörper 11 wird vorzugsweise eine Ni-Legierung verwendet, dabei kann Chrom und/oder Yttrium in der Legierung enthalten sein. Figure 1 shows schematic representations of the center electrode 10. The center electrode 10 has an electrode base body 11 and a core 12, which is arranged within the electrode base body 12. The core 11 consists of a material with a higher thermal conductivity than the material of the electrode base body 11. Typically, the material of the electrode base body 11 has a higher wear resistance than the material of the core 12. The core 12 consists of copper, silver or an alloy with copper and / or silver. A Ni alloy is preferably used as the material for the electrode base body 11, and the alloy can contain chromium and / or yttrium.

Aufgrund des Herstellungsverfahrens, hier ein Fließpress-Verfahren, weist der Kern der hier im Schnitt gezeigten Mittelelektrode 10 mindestens einen ersten Abschnitt 15a auf, in dem der Kern 12 einen relativ konstanten Durchmesser dK hat. Mit dem Begriff "relativ konstant" ist im Sinne dieser Anmeldung gemeint, dass der Durchmesser dK in dem Abschnitt seinen Wert maximal um 5% verändert.Due to the manufacturing process, here an extrusion process, the core of the center electrode 10 shown here in section has at least one first section 15a in which the core 12 has a relatively constant diameter d K. In the context of this application, the term “relatively constant” means that the diameter d K in the section changes its value by a maximum of 5%.

Innerhalb einem zweiten Abschnitt 14a reduziert sich der Durchmesser dK des Kerns 12. Der mindestens eine erste Abschnitt 15a ist an einer dem Brennraum abgewandten Seite der Mittelelektrode 10 angeordnet, wobei ein hier nicht gezeigter Elektrodenkopf 4 im Anschluss an das Brennraum-abgewandte Ende des ersten Abschnitts 15 ausgebildet ist. In Richtung des Brennraums schließt sich der zweite Abschnitt 14a an den mindestens einen ersten Abschnitt 15a an. Grundsätzlich ist es denkbar, dass der Kern 12 mehrere erste Abschnitte 15a mit konstanten Durchmessern dK aufweist, wobei die Durchmesser dK der einzelnen ersten Abschnitte 15a unterschiedlich sind. Dies ist insbesondere der Fall, wenn die Mittelelektrode 10 bzw. der Elektrodengrundkörper 11 selbst mehrere Bereiche mit unterschiedlichen Durchmessern dE aufweist. Im Fall von mehreren ersten Abschnitten 15a des Kerns ist der dem Brennraum am nächsten gelegenen Abschnitt der zweite Abschnitt 14a mit dem sich kontinuierlich verringern Durchmesser dK des Kerns 12.The diameter d K of the core 12 is reduced within a second section 14a. The at least one first section 15a is arranged on a side of the center electrode 10 facing away from the combustion chamber, with an electrode head 4 (not shown here) following the end of the first facing away from the combustion chamber Section 15 is formed. In the direction of the combustion chamber, the second section 14a adjoins the at least one first section 15a. In principle, it is conceivable that the core 12 has a plurality of first sections 15a with constant diameters d K , the diameters d K of the individual first sections 15a being different. This is particularly the case when the center electrode 10 or the electrode base body 11 itself has a plurality of regions with different diameters d E. In the case of a plurality of first sections 15a of the core, the section closest to the combustion chamber is the second section 14a with the continuously decreasing diameter d K of the core 12.

Die in Figur 1 dargestellte Mittelelektrode 10 ist aus einem Elektrodengrundkörper 11 aufgebaut, der entlang seiner Länge einen konstanten Durchmesser dE aufweist und somit auch die Mittelelektrode 10 einen konstanten Durchmesser dE aufweist. Beim dem Elektrodengrundkörper 11 kann man mindestens drei Bereiche 13, 14, 15 unterscheiden. In einem ersten Bereich 15 weist der Elektrodengrundkörper 11 einen Kern 12 mit konstantem Durchmesser dK auf. In einem zweiten Bereich 14a weist der Elektrodengrundkörper 11 einen Kern 12 mit einem sich kontinuierlich reduzierenden Durchmesser dK auf. In einem dritten Bereich 13 weist der Elektrodengrundkörper 11 keinen Kern auf.In the Figure 1 The center electrode 10 shown is constructed from an electrode base body 11 which has a constant diameter d E along its length and thus the center electrode 10 also has a constant diameter d E. In the case of the electrode base body 11, at least three areas 13, 14, 15 can be distinguished. In a first region 15, the electrode base body 11 has a core 12 with a constant diameter d K. In a second region 14a, the electrode base body 11 has a core 12 with a continuously reducing diameter d K. In a third region 13, the electrode base body 11 does not have a core.

Die Dicke c des Mantels des Elektrodengrundkörpers 11 ergibt sich aus der halben Differenz des Elektrodengrundkörper-Durchmessers dE zu dem Kern-Durchmesser dK. Wenn der Elektrodengrundköper 11 in dem ersten Bereich 15 einen konstanten Durchmesser dE1 aufweist, dann ist die Manteldicke c in diesem ersten Bereich 15 konstant. Vorteilhaft ist vorgesehen, dass in diesem ersten Bereich 15 die Manteldicke c des Elektrodengrundkörpers 11 nicht kleiner als 0,15 mm und nicht größer ist als 0,35 mm, beispielsweise ist die Manteldicke c gleich 0,25 mm oder kleiner.The thickness c of the jacket of the electrode base body 11 results from half the difference between the electrode base body diameter d E and the core diameter d K. If the electrode base body 11 has a constant diameter d E1 in the first region 15, then the jacket thickness c in this first region 15 is constant. It is advantageously provided that in this first region 15 the jacket thickness c of the electrode base body 11 is not less than 0.15 mm and not greater than 0.35 mm, for example the jacket thickness c is 0.25 mm or less.

Im zweiten Bereich 14 kann der Elektrodengrundkörper 11 einen konstanten Durchmesser dE2 aufweisen, wobei in diesem Fall die Manteldicke c innerhalb des Bereichs 14 in Richtung des Brennraums zunimmt. Die Manteldicke c ist im Bereich 14 mindestens 0,15 mm dick.In the second region 14, the electrode base body 11 can have a constant diameter d E2 , in which case the jacket thickness c increases within the region 14 in the direction of the combustion chamber. The jacket thickness c is at least 0.15 mm thick in the region 14.

Erfindungsgemäß reduziert sich der Durchmesser dE2 des Elektrodengrundkörpers 11 im zweiten Bereich 14 ebenfalls. n diesem Fall gilt für die Manteldicke c, dass diese vorzugsweise im Bereich von 0,15 mm bis 0,35 mm liegt. Es kann vorgesehen sein, dass der Durchmesser dE2 des Elektrodengrundkörpers 11 sich mit der gleichen Rate wie der Durchmesser dK des Kerns 12 ändert. Dies hat den Vorteil, dass die Manteldicke c in dem zweiten Bereich 14 konstant bleibt.According to the invention, the diameter d E2 of the electrode base body 11 is also reduced in the second region 14. In this case it applies to the jacket thickness c that it is preferably in the range from 0.15 mm to 0.35 mm. It can be provided that the diameter d E2 of the electrode base body 11 changes at the same rate as the diameter d K of the core 12. This has the advantage that the jacket thickness c remains constant in the second region 14.

Im dritten Bereich 13 des Elektrodengrundkörpers 11 gibt es keinen Kern und somit entsprich die Manteldicke c dem halben Durchmesser dE3 des Elektrodengrundkörpers 11. Der dritte Bereich 13 weist einen konstanten Durchmesser dE3 auf, der dem Durchmesser dE2 des zweiten Bereichs 14 beim Übergang zum dritten Bereich 13 entspricht.In the third area 13 of the electrode base body 11 there is no core and thus the jacket thickness c corresponds to half the diameter d E3 of the electrode base body 11. The third area 13 has a constant diameter d E3 , which corresponds to the diameter d E2 of the second area 14 at the transition to third area 13 corresponds.

Der dritte Bereich 13 des Elektrodengrundkörpers 11 weist eine Länge b auf, die sich von einem brennraumseitigen Ende 17 des Kerns 12 bis zu einer brennraumseitigen Stirnfläche 16 des Elektrodengrundkörpers 11 erstreckt. Die Länge b ist nicht größer als 3,5 mm. Wenn die Mittelelektrode 10 mit einer edelmetallhaltige Zündfläche 19 ausgebildet ist, kann die Länge b kürzer als ohne edelmetallhaltige Zündfläche 19 ausgebildet sein, wie in Figur 1b gezeigt. Wenn auf eine edelmetallhaltige Zündfläche 19 verzichtet wird, wie in Figur 1a gezeigt, dann sollte die Länge b eine Mindestlänge von 0,6 mm aufweisen, damit der Edelmetallgrundkörper 12 genug Material für eine ausreichend lange Lebensdauer der Mittelelektrode 10 aufweist. Bei der Verwendung einer edelmetallhaltige Zündfläche 19 reicht eine Länge b von mindestens 0,2 mm für eine ausreichend lange Lebensdauer der Mittelelektrode 10.The third region 13 of the electrode base body 11 has a length b which extends from an end 17 of the core 12 on the combustion chamber side to an end face 16 of the electrode base body 11 on the combustion chamber side. The length b is not greater than 3.5 mm. If the center electrode 10 is designed with a noble metal-containing ignition surface 19, the length b can be made shorter than without a noble metal-containing ignition surface 19, as in FIG Figure 1b shown. If a noble metal-containing ignition surface 19 is dispensed with, as in Figure 1a shown, then the length b should have a minimum length of 0.6 mm so that the noble metal base body 12 has enough material for a sufficiently long service life of the center electrode 10. When using a noble metal-containing ignition surface 19, a length b of at least 0.2 mm is sufficient for a sufficiently long service life of the center electrode 10.

Figur 2 zeigt ein Beispiel für einen Querschnitt der Mittelelektrode 10. Der Durchmesser dE der Mittelelektrode 10 und des Elektrodengrundkörpers 11 ist kleiner als 1,7 mm. Mittig im Querschnitt der Mittelelektrode 10 bzw. des Elektrodengrundkörpers 11 ist der Querschnitt des Kerns 12 angeordnet. Die Dicke c des Mantels des Elektrodengrundkörpers 11 ergibt sich aus der halben Differenz des Elektrodengrundkörper-Durchmessers dE zu dem Kern-Durchmesser dK. Vorteilhafterweise haben die Querschnitte des Elektrodengrundkörpers 11 und des Kerns 12 die gleiche geometrische Form. Figure 2 shows an example of a cross section of the center electrode 10. The diameter d E of the center electrode 10 and the electrode base body 11 is less than 1.7 mm. The cross section of the core 12 is arranged centrally in the cross section of the center electrode 10 or of the electrode base body 11. The thickness c of the jacket of the electrode base body 11 results from half the difference between the electrode base body diameter d E and the core diameter d K. The cross-sections of the electrode base body 11 and of the core 12 advantageously have the same geometric shape.

Figur 3 zeigt eine schematische Darstellung einer Zündkerze 1 mit einer erfindungsgemäßen Mittelelektrode 10. Die Zündkerze 1 weist ein metallisches Gehäuse 2 mit einem Gewinde für die Montage der Zündkerze 1 in einem Zylinderkopf auf. Des Weiteren weist das Gehäuse eine Sechskant Abschnitt 9 auf, an dem ein Werkzeug für die Montage der Zündkerze 1 in den Zylinderkopf angesetzt wird. Innerhalb des Gehäuses 2 ist ein Isolator 3 angeordnet. Eine Mittelelektrode 10 und ein Anschlussbolzen 7 sind innerhalb des Isolators 3 angeordnet und über ein Widerstandselement 6 elektrisch verbunden. Figure 3 shows a schematic representation of a spark plug 1 with a central electrode 10 according to the invention. The spark plug 1 has a metallic housing 2 with a thread for mounting the spark plug 1 in a cylinder head. Furthermore, the housing has a hexagon section 9, on which a tool for mounting the spark plug 1 in the cylinder head is attached. An insulator 3 is arranged inside the housing 2. A center electrode 10 and a connecting bolt 7 are arranged inside the insulator 3 and are electrically connected via a resistance element 6.

Auf der Innenseite des Isolators 3 ist ein Sitz (3a) ausgebildet, auf dem die Mittelelektrode (10) mit Ihrem Mittelelektrodenkopf (4) aufliegt. Der Isolator (3) hat im Bereich des Sitzes (3a) eine Wandstärke von nicht kleiner als 2 mm.On the inside of the insulator 3 there is a seat (3a) on which the center electrode (10) rests with its center electrode head (4). The insulator (3) has a wall thickness of not less than 2 mm in the area of the seat (3a).

Die Mittelelektrode 10 ragt typischerweise am brennraumseitigen Ende der Zündkerze 1 aus dem Isolator 3 raus. Die Mittelelektrode weist eine Grundkörper 10 und eine am brennraumseitigen Ende des Grundkörpers angeordnete Zündfläche 19 auf. Der Grundkörper 10 hat einen Kern 12, der von einem Mantel 11 umgeben ist.The center electrode 10 typically protrudes from the insulator 3 at the end of the spark plug 1 on the combustion chamber side. The center electrode has a base body 10 and an ignition surface 19 arranged on the end of the base body on the combustion chamber side. The base body 10 has a core 12 which is surrounded by a jacket 11.

Am brennraumseitigen Ende des Gehäuses 2 ist eine Masseelektrode 5 angeordnet. Die gemeinsam mit der Mittelelektrode 10 einen Zündspalt bildet. Die Masseelektrode 5 kann als Dachelektrode, Seitenelektrode oder Bügelelektrode ausgebildet sein.A ground electrode 5 is arranged at the end of the housing 2 on the combustion chamber side. Which forms an ignition gap together with the center electrode 10. The ground electrode 5 can be designed as a roof electrode, side electrode or bracket electrode.

Claims (9)

  1. Spark plug (1), having a housing (2), an insulator (3) which is arranged in the housing (2), a centre electrode (10) which is arranged in the insulator (3), and an earth electrode (5) which is arranged on the housing (2), wherein the earth electrode (5) and the centre electrode (10) are arranged in relation to one another such that the earth electrode (5) and the centre electrode (10) form a spark gap, and wherein the centre electrode (10), by way of an electrode head (4), rests on a seat (3a) which is formed on an inner side of the insulator (3), and wherein the centre electrode (10) has an electrode main body (11) and a core (12) which is arranged in the electrode main body (11), wherein the core (12) consists of a material which has a higher thermal conductivity than the material of the electrode main body (11), wherein the electrode main body (11) has a diameter (dE) of not greater than 1.7 mm, wherein the electrode main body (11) has a first region (15), a second region (14) on the combustion chamber side thereof and a third region (13) once again on the combustion chamber side thereof, wherein the electrode main body (11) has a constant diameter (dE1) and the core (12) has a constant diameter (dK) in the first region (15), wherein the electrode main body (11) has a core (12) with a continuously reducing diameter (dK) in the second region (14a), and the electrode main body (11) does not have a core in the third region (13), wherein the diameter (dE2) of the electrode main body (11) is likewise reduced in the second region (14), characterized in that the electrode main body (11) has a constant diameter (dE3) in the third region (13), which constant diameter corresponds to the diameter (dE2) of the electrode main body (11) in the second region (14) at the transition to the third region (13).
  2. Spark plug (1) according to Claim 1, characterized in that the insulator (3) has a wall thickness of not less than 2 mm in the region of the seat (3a) which is formed on its inner side.
  3. Spark plug (1) according to either of Claims 1 and 2, characterized in that the cross-sectional area of the core (12) corresponds to at least 20% of the total cross-sectional area of the electrode (10) in the at least one first region (15).
  4. Spark plug (1) according to one of the preceding claims, characterized in that the cross-sectional area of the core (12) corresponds to at most 65% of the total cross-sectional area of the electrode (10) in the at least one first region (15).
  5. Spark plug (1) according to one of the preceding claims, characterized in that the electrode main body (11) has a casing thickness c of at least 0.15 mm, and in particular of at most 0.35 mm, in particular in the at least one first region (15).
  6. Spark plug (1) according to one of the preceding claims, characterized in that the distance b between the end (16) of the electrode main body (11) and an end (17) of the core (12) that faces the combustion chamber is not greater than 3.5 mm, and in particular not less than 0.2 mm, at a combustion chamber-side end (16) of the electrode main body (11).
  7. Spark plug (1) according to one of Claims 1 to 6, characterized in that the at least one first region (15) is longer than the diameter of the electrode main body (11) .
  8. Spark plug (1) according to one of the preceding claims, characterized in that the cross-sectional area of the core (12) and the cross-sectional area of the electrode main body (11) have the same shape.
  9. Spark plug (1) according to one of the preceding claims, characterized in that the electrode main body (11) contains a nickel-containing alloy, in particular in that the alloy contains at least 20% by weight of chromium.
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US10250015B2 (en) 2019-04-02
KR20170094230A (en) 2017-08-17
WO2016096462A1 (en) 2016-06-23
JP6753852B2 (en) 2020-09-09
EP3235079A1 (en) 2017-10-25
ES2865177T3 (en) 2021-10-15
JP2017538270A (en) 2017-12-21
DE102014226107A1 (en) 2016-06-16
US20170346260A1 (en) 2017-11-30
CN107005029A (en) 2017-08-01

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