EP2012397B1 - Spark plug and method for its production - Google Patents

Spark plug and method for its production Download PDF

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Publication number
EP2012397B1
EP2012397B1 EP08012086.8A EP08012086A EP2012397B1 EP 2012397 B1 EP2012397 B1 EP 2012397B1 EP 08012086 A EP08012086 A EP 08012086A EP 2012397 B1 EP2012397 B1 EP 2012397B1
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EP
European Patent Office
Prior art keywords
molded part
ground electrode
intermediate piece
welded
noble
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EP08012086.8A
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German (de)
French (fr)
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EP2012397A2 (en
EP2012397A3 (en
Inventor
Werner Niessner
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Federal Mogul Ignition GmbH
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Federal Mogul Ignition GmbH
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Priority claimed from DE102007052266.7A external-priority patent/DE102007052266B4/en
Application filed by Federal Mogul Ignition GmbH filed Critical Federal Mogul Ignition GmbH
Publication of EP2012397A2 publication Critical patent/EP2012397A2/en
Publication of EP2012397A3 publication Critical patent/EP2012397A3/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
    • H01T13/32—Sparking plugs characterised by features of the electrodes or insulation characterised by features of the earthed electrode
    • 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
    • H01T21/00—Apparatus or processes specially adapted for the manufacture or maintenance of spark gaps or sparking plugs
    • H01T21/02—Apparatus or processes specially adapted for the manufacture or maintenance of spark gaps or sparking plugs of sparking plugs

Definitions

  • the invention relates to a spark plug with the features specified in the preamble of claim 1 and of a method with the features specified in the preamble of claim 4.
  • a spark plug which has a cylindrical center electrode made of copper with a jacket made of a highly heat-resistant nickel alloy. To increase the life of the center electrode is reinforced with a tip of a precious metal material.
  • the EP 1 517 418 A2 discloses alloys of more than 50% by weight of iridium with at least one further metal or metal oxide from the group consisting of platinum, rhodium, nickel, tungsten, palladium, ruthenium, rhenium, aluminum, aluminum oxide, yttrium and yttrium oxide.
  • the iridium alloy tip is butt welded to the forward end of the base center electrode.
  • connection zone By subjecting the connection zone to a laser beam which is passed around the electrode, an alloy is formed in the connection zone, which consists of components of the non-noble center electrode and the electrode tip of the iridium alloy.
  • the alloy zone is intended to mitigate thermal stresses resulting from the different thermal expansion coefficients of the iridium alloy and the copper.
  • the coefficient of thermal expansion is between about 6 x 10 -6 K -1 and 7 x 10 -6 K -1 for platinum alloys between 9 x 10 -6 K -1 and 11 x 10 -6 K -1 .
  • the coefficient of thermal expansion is 16 ⁇ 10 -6 K -1 , for nickel-based alloys between 10.5 ⁇ 10 -6 K -1 and 14.5 ⁇ 10 -6 K -1 .
  • the ground electrode of the known spark plug is formed as usual from a flat wire with a rectangular cross-section and consists of a highly heat-resistant nickel-based alloy. It is reinforced with a molding of a platinum alloy with more than 50 wt .-% platinum and with at least one metal from the group iridium, rhodium, nickel, tungsten, palladium, ruthenium and rhenium. As a molding reveals the EP 1 517 418 A2 a blank, which is welded with a laser on the base ground electrode. It is disadvantageous that the non-noble ground electrode has a substantially different shape and arrangement than the center electrode of the spark plug.
  • connection zone between the molded part formed from the platinum alloy and the base ground electrode, which projects beyond the molded part from the platinum alloy, is much worse to achieve with a laser beam than the connecting zone between the center electrode and its tip consisting of the iridium alloy.
  • an alloying zone covering the entire cross section of the platinum alloy molding, which is formed from the platinum alloy and the nickel-based alloy, is difficult or impossible to achieve.
  • this causes the bonding zone between the platinum alloy molding member and the ground electrode to be stressed by thermal stresses more than the bonding zone between the center electrode and its electrode tip formed from an iridium alloy.
  • cracking is observed in the junction zone between the ground electrode and the platinum alloy molding, which can lead to premature termination of the spark plug life, until the platinum alloy is removed.
  • EP 1 416 599 A2 to provide a 0.2 mm iridium alloy wafer with 40% by weight nickel between the base non-noble electrode and the precious metal alloy molding, which in this case is an iridium alloy or a platinum alloy.
  • This disc is first welded by resistance welding to the base ground electrode, which according to the disclosure of EP 1 416 599 A2 as well as the center electrode consists of Inconel 600. Thereafter, a molded article of the iridium or platinum alloy, which is cylindrical and at its one end has a larger diameter flange, welded to this flange by resistance welding on the already welded to the ground electrode disc made of iridium nickel. Thereafter, a laser beam is applied to the connection zone to improve the weld joint.
  • the iridium-40% nickel iridium washer provided between the non-noble ground electrode and the iridium or platinum alloy mold achieves thermal stresses in the junction zone between the Inconel 600 and the IrNi40 disk, as well as the thermal stresses between the IrNi40 and the molding of the nobler iridium or platinum alloy are lower than the thermal stresses between Inconel 600 and the iridium or platinum alloy molding without inserting the IrNi40 disk.
  • IrNi40 has a linear thermal expansion coefficient that is between that of the ground electrode and that of the iridium or platinum alloy molding.
  • the EP 1 376 791 A1 discloses between the non-noble ground electrode and the noble molding, with which the ground electrode is to be equipped, an intermediate piece - in particular of a noble metal alloy - provide, the linear expansion coefficient of which neither matches the ground electrode with that of the noble molding, but intervenes.
  • a spark plug with the features specified in the preamble of claim 1 discloses the JP 2005-203110 A , Thereafter, it is known, a prefabricated rivet-shaped Composite part, which consists of a precious metal molding and an intermediate piece, which consists of the same base metal material as the ground electrode to weld butt to the ground electrode.
  • the ground electrode is provided with a blind hole, in which a precious metal molded part is inserted and welded to the ground electrode.
  • EP1341282 discloses the preamble of claims 1 and 4.
  • the present invention has for its object to provide a way how the life of a generic spark plug can be extended.
  • nickel-based alloys particularly, z. Inconel materials, in particular Inconel 600.
  • Other well-suited alloys are nickel-based alloys containing 1.5 to 2.5% by weight of silicon, 1.5 to 3% by weight of aluminum, up to 0.5% by weight of manganese and 0.05 to 0.2 wt .-% of titanium in combination with 0.1 to 0.3 wt .-% zirconium and the remainder of nickel, wherein the zirconium may be wholly or partially replaced by the double mass hafnium
  • Another suitable nickel-base alloy contains 1.5 to 2.5% by weight of silicon, 1.5 to 3% by weight of aluminum, up to 0.5% by weight of manganese and 0.005 to 0.2% by weight. Yttrium in combination with 0.05 to 0.3 wt .-% lanthanum and the balance nickel.
  • platinum, iridium and their base alloys are particularly suitable platinum, iridium and their base alloys.
  • platinum-based alloys are mainly iridium, rhodium, ruthenium, palladium, tungsten, nickel and osmium as alloying components into consideration.
  • iridium-based alloys are mainly platinum, rhodium, palladium, rhenium and chromium as alloying components into consideration.
  • Particularly suitable are iridium-rhodium alloys, in particular iridium with 10 wt .-% rhodium.
  • the noble metal materials for the molding may contain small amounts of oxides of one or more of the elements zirconium, yttrium, hafnium, cerium, titanium, magnesium, barium and lanthanum, taken together preferably 0.05 to 1 wt .-%.
  • the intermediate piece or a composite part formed from the non-precious intermediate piece and the noble molded part can be connected to the ground electrode in different ways. One possibility is to provide a continuous hole in the base ground electrode and to insert the composite part formed from the shaped part and the intermediate piece into the through hole in such a way that the intermediate piece can be welded thereto at the side facing away from the center electrode of the ground electrode.
  • the precious metal-containing molded part should terminate flush with the center electrode facing surface of the ground electrode.
  • claim 4 is a method for reinforcing a ground electrode for a spark plug having the features of claim 1.
  • the noble metal-containing molded part, with which the ground electrode is to be reinforced welded to an intermediate piece of a material whose thermal expansion coefficient does not deviate from the thermal expansion coefficient of the base ground electrode.
  • the composite part formed from the molded part and the intermediate piece is then inserted into the through hole of the ground electrode so that the molded part is flush with the surface of the ground electrode facing the center electrode, and is welded to the base ground electrode.
  • the welded connection takes place on the center electrode opposite side of the ground electrode, and preferably by laser welding.
  • the ground electrode usually consists of a profile wire with a rectangular profile, from which a straight section is separated and welded to the body of the spark plug. Only then is the ground electrode bent towards the center electrode.
  • the composite part, with which the ground electrode is to be reinforced, is preferably welded to the ground electrode as long as the ground electrode is not yet bent towards the center electrode, but is still straight. This considerably facilitates the welding of the composite part to the ground electrode.
  • the molded part and the intermediate piece are first provisionally connected to each other and then welded by means of a laser.
  • Preliminary bonding can be accomplished by butting them together by electrical resistance welding.
  • Another possibility is to butt the molded part and the intermediate piece by cold welding, for. B. by friction welding or by compression with simultaneous increase in diameter by upsetting. Electrical resistance welding and cold welding are known per se as a method of making bimetallic contact rivets.
  • a composite part is formed by provisionally connecting the molded part to the intermediate piece, its connecting zone can be processed by laser welding in such a way that an alloy zone is formed which extends over the entire cross section of the composite part.
  • the composite part is expediently rotated about its own longitudinal axis, while its connection zone is located in the area of action of the laser beam and is hit all around by the laser beam.
  • the molded part and the intermediate piece can be cut off from a wire-shaped semifinished product and then joined together. But it is also possible to provisionally connect two wire-shaped semi-finished products at their ends first and then cut them from the respective semifinished product and to weld additionally with a laser. Finally, it is possible, a cut off from the semi-finished, consisting mainly of precious metal molding provisionally with the end of a base wire-shaped semifinished product to connect and only then to separate the composite part of non-precious semi-finished product. The latter approach is preferred.
  • FIG. 1 shows a spark plug with a spark plug body 1 made of a highly heat-resistant alloy, for. B. of a nickel-based alloy.
  • a ceramic insulator 2 is disposed, in which a center electrode 3 is embedded, which may be made of copper and is reinforced with a noble metal tip 5, which is welded to the front end of the center electrode 3 to form a connection zone 7, in which a Alloy of the constituents of the materials for the center electrode 3 and the noble metal tip 5 is present.
  • a ground electrode 4 is welded, which usually consists of a nickel alloy.
  • the ground electrode 4 is formed from a profile wire having a rectangular cross-section and formed as a roof electrode, that is, it is bent at right angles, so that its bent portion of the noble metal tip 5 of the center electrode 3 is opposite.
  • the ground electrode 4 is reinforced with a predominantly made of precious metal molded part 6, which is welded to a base 9, which serves as an intermediate piece between the ground electrode 4 and the predominantly made of precious metal molding 6, which forms a the entire cross section of the base 9 detecting connecting zone 8 is welded to the base 9.
  • In the connection zone 8 is an alloy of the constituents of the materials from which the intermediate piece 9 (the base) and the molded part 6 exist.
  • the noble metal tip 5 and the molded part 6 formed of noble metal face each other at a predetermined distance.
  • a molded part 6 is welded by electrical resistance welding.
  • the molded part 6 is a section of a predominantly made of precious metal wire-shaped semifinished product whose diameter is slightly smaller than that of the semifinished product 10.
  • the connection zone 8 between them with a laser processed, which is led around the connection zone 8.
  • the composite of the semifinished product 10 and the molded part 6 can be rotated about its longitudinal axis 11, wherein the laser remains stationary directed to the connection zone 8.
  • connection zone 8 which consists of the constituents of the materials of the wire sections involved and extends over the entire cross section of the molded part 6 and the intermediate piece 9.
  • a composite part 12 which consists of the molded part 6, the connection zone 8 and an intermediate piece 9 of the semifinished product 10, separated from the semifinished product 10 and welded to the ground electrode 4.
  • FIG. 2a shows a way to arm the ground electrode 4, namely by means of a composite part 12, the intermediate piece 9 is provided with a head 9a, which may be formed by upsetting.
  • a composite part 12 is inserted from behind into a through hole 14 of the ground electrode 4 and welded to it at the side facing away from the center electrode 3 of the ground electrode 4, where the head 9a abuts against the ground electrode 4.
  • the welding can be done by laser welding alone.
  • the molded part 6 is flush with the surface of the ground electrode 4.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Spark Plugs (AREA)

Description

Die Erfindung geht von einer Zündkerze mit den im Oberbegriff des Anspruchs 1 angegebenen Merkmalen und von einem Verfahren mit den im Oberbegriff des Anspruchs 4 angegebenen Merkmalen aus.The invention relates to a spark plug with the features specified in the preamble of claim 1 and of a method with the features specified in the preamble of claim 4.

Aus der EP 1 517 418 A2 ist eine Zündkerze bekannt, welche eine zylindrische Mittelelektrode aus Kupfer mit einem Mantel aus einer hochwärmebeständigen Nickellegierung hat. Zur Erhöhung der Lebensdauer ist die Mittelelektrode mit einer Spitze aus einem Edelmetallwerkstoff armiert. Die EP 1 517 418 A2 offenbart dafür Legierungen aus mehr als 50 Gew.-% Iridium mit wenigstens einem weiteren Metall oder Metalloxid aus der Gruppe Platin, Rhodium, Nickel, Wolfram, Palladium, Ruthenium, Rhenium, Aluminium, Aluminiumoxid, Yttrium und Yttriumoxid. Die Spitze aus der Iridiumlegierung wird stumpf auf das vordere Ende der unedlen Mittelelektrode geschweißt. Durch Beaufschlagen der Verbindungszone mit einem Laserstrahl, der um die Elektrode herumgeführt wird, wird in der Verbindungszone eine Legierung gebildet, welche aus Bestandteilen der unedlen Mittelelektrode und der Elektrodenspitze aus der Iridiumlegierung besteht. Die Legierungszone soll Wärmespannungen mildern, die sich aus den unterschiedlichen thermischen Längenausdehnungskoeffizienten der Iridiumlegierung und des Kupfers ergeben. Für Iridiumlegierungen beträgt der Wärmeausdehnungskoeffizient ungefähr zwischen 6 x 10-6 K-1 und 7 x 10-6 K-1 für Platinlegierungen zwischen 9 x 10-6 K-1 und 11 x 10-6 K-1. Für Kupfer beträgt der Wärmeausdehnungskoeffizient 16 x 10-6 K-1, für Nickelbasislegierungen zwischen 10,5 x 10-6 K-1 und 14,5 x 10-6 K-1.From the EP 1 517 418 A2 For example, a spark plug is known which has a cylindrical center electrode made of copper with a jacket made of a highly heat-resistant nickel alloy. To increase the life of the center electrode is reinforced with a tip of a precious metal material. The EP 1 517 418 A2 discloses alloys of more than 50% by weight of iridium with at least one further metal or metal oxide from the group consisting of platinum, rhodium, nickel, tungsten, palladium, ruthenium, rhenium, aluminum, aluminum oxide, yttrium and yttrium oxide. The iridium alloy tip is butt welded to the forward end of the base center electrode. By subjecting the connection zone to a laser beam which is passed around the electrode, an alloy is formed in the connection zone, which consists of components of the non-noble center electrode and the electrode tip of the iridium alloy. The alloy zone is intended to mitigate thermal stresses resulting from the different thermal expansion coefficients of the iridium alloy and the copper. For iridium alloys, the coefficient of thermal expansion is between about 6 x 10 -6 K -1 and 7 x 10 -6 K -1 for platinum alloys between 9 x 10 -6 K -1 and 11 x 10 -6 K -1 . For copper, the coefficient of thermal expansion is 16 × 10 -6 K -1 , for nickel-based alloys between 10.5 × 10 -6 K -1 and 14.5 × 10 -6 K -1 .

Die Masseelektrode der bekannten Zündkerze ist wie üblich aus einem Flachdraht mit rechteckigem Querschnitt gebildet und besteht aus einer hochwärmebeständigen Nickelbasislegierung. Sie ist mit einem Formteil aus einer Platinlegierung mit mehr als 50 Gew.-% Platin und mit wenigstens einem Metall aus der Gruppe Iridium, Rhodium, Nickel, Wolfram, Palladium, Ruthenium und Rhenium armiert. Als Formteil offenbart die EP 1 517 418 A2 eine Ronde, welche mit einem Laser auf die unedle Masseelektrode geschweißt wird. Dabei macht es sich nachteilig bemerkbar, dass die unedle Masseelektrode eine wesentlich andere Gestalt und Anordnung als die Mittelelektrode der Zündkerze hat. Die Verbindungszone zwischen dem aus der Platinlegierung gebildeten Formteil und der unedlen Masseelektrode, welche allseits über das Formteil aus der Platinlegierung übersteht, ist mit einem Laserstrahl wesentlich schlechter zu erreichen als die Verbindungszone zwischen der Mittelelektrode und ihrer aus der Iridiumlegierung bestehenden Spitze. Die Folge davon ist, dass eine den ganzen Querschnitt des Formteils aus der Platinlegierung erfassende Legierungszone, welche aus der Platinlegierung und aus der Nickelbasislegierung gebildet ist, schwer oder gar nicht zu erreichen ist. Das führt in der Praxis dazu, dass die Verbindungszone zwischen dem Formteil aus der Platinlegierung und der Masseelektrode durch Wärmespannungen stärker beansprucht wird als die Verbindungszone zwischen der Mittelelektrode und ihrer aus einer Iridiumlegierung gebildeten Elektrodenspitze. Infolge der stärkeren Wärmespannungen wird in der Verbindungszone zwischen der Masseelektrode und dem Formteil aus der Platinlegierung eine Rissbildung beobachtet, welche bis zum Ablösen des Formteils aus der Platinlegierung und damit zu einem vorzeitigen Ende der Lebensdauer der Zündkerze führen kann.The ground electrode of the known spark plug is formed as usual from a flat wire with a rectangular cross-section and consists of a highly heat-resistant nickel-based alloy. It is reinforced with a molding of a platinum alloy with more than 50 wt .-% platinum and with at least one metal from the group iridium, rhodium, nickel, tungsten, palladium, ruthenium and rhenium. As a molding reveals the EP 1 517 418 A2 a blank, which is welded with a laser on the base ground electrode. It is disadvantageous that the non-noble ground electrode has a substantially different shape and arrangement than the center electrode of the spark plug. The connection zone between the molded part formed from the platinum alloy and the base ground electrode, which projects beyond the molded part from the platinum alloy, is much worse to achieve with a laser beam than the connecting zone between the center electrode and its tip consisting of the iridium alloy. The result of this is that an alloying zone covering the entire cross section of the platinum alloy molding, which is formed from the platinum alloy and the nickel-based alloy, is difficult or impossible to achieve. In practice, this causes the bonding zone between the platinum alloy molding member and the ground electrode to be stressed by thermal stresses more than the bonding zone between the center electrode and its electrode tip formed from an iridium alloy. As a result of the higher thermal stresses, cracking is observed in the junction zone between the ground electrode and the platinum alloy molding, which can lead to premature termination of the spark plug life, until the platinum alloy is removed.

Um dem zu begegnen, offenbart die EP 1 416 599 A2 , zwischen der unedlen Masseelektrode und dem Formteil aus der Edelmetalllegierung, welche in diesem Fall eine Iridiumlegierung oder eine Platinlegierung ist, eine 0,2 mm dünne Scheibe aus einer Iridiumlegierung mit 40 Gew.-% Nickel vorzusehen. Diese Scheibe wird zunächst durch Widerstandsschweißen auf die unedle Masseelektrode geschweißt, welche nach der Offenbarung der EP 1 416 599 A2 ebenso wie die Mittelelektrode aus Inconel 600 besteht. Danach wird ein Formteil aus der Iridium- oder Platinlegierung, welches zylindrisch ist und an seinem einen Ende einen im Durchmesser größeren Flansch hat, mit diesem Flansch durch Widerstandsschweißen auf die bereits auf die Masseelektrode geschweißte Scheibe aus Iridium-Nickel geschweißt. Danach wird die Verbindungszone mit einem Laserstrahl beaufschlagt, um die Schweißverbindung zu verbessern.To counter this, the reveals EP 1 416 599 A2 to provide a 0.2 mm iridium alloy wafer with 40% by weight nickel between the base non-noble electrode and the precious metal alloy molding, which in this case is an iridium alloy or a platinum alloy. This disc is first welded by resistance welding to the base ground electrode, which according to the disclosure of EP 1 416 599 A2 as well as the center electrode consists of Inconel 600. Thereafter, a molded article of the iridium or platinum alloy, which is cylindrical and at its one end has a larger diameter flange, welded to this flange by resistance welding on the already welded to the ground electrode disc made of iridium nickel. Thereafter, a laser beam is applied to the connection zone to improve the weld joint.

Durch die zwischen der unedlen Masseelektrode und dem Formteil aus der Iridium- oder Platinlegierung vorgesehene Scheibe aus Iridium mit 40 % Nickel wird erreicht, dass die Wärmespannungen in der Verbindungszone zwischen dem Inconel 600 und der Scheibe aus IrNi40 sowie die Wärmespannungen zwischen der Scheibe aus IrNi40 und dem Formteil aus der edleren Iridium- oder Platinlegierung geringer sind als es die Wärmespannungen zwischen Inconel 600 und dem Formteil aus der Iridium- oder Platinlegierung ohne Einfügen der Scheibe aus IrNi40 wären. Der Grund dafür liegt darin, dass IrNi40 einen linearen thermischen Ausdehnungskoeffizienten hat, der zwischen dem der Masseelektrode und dem des Formteils aus der Iridium- oder Platinlegierung liegt.The iridium-40% nickel iridium washer provided between the non-noble ground electrode and the iridium or platinum alloy mold achieves thermal stresses in the junction zone between the Inconel 600 and the IrNi40 disk, as well as the thermal stresses between the IrNi40 and the molding of the nobler iridium or platinum alloy are lower than the thermal stresses between Inconel 600 and the iridium or platinum alloy molding without inserting the IrNi40 disk. The reason for this is that IrNi40 has a linear thermal expansion coefficient that is between that of the ground electrode and that of the iridium or platinum alloy molding.

Es bleibt jedoch der Nachteil, dass es sowohl beim Aufschweißen der dünnen Scheibe aus IrNi40 auf das Inconel 600 als auch beim Aufschweißen des Formteils aus der edleren Iridium- oder Platinlegierung auf die dünne Scheibe aus IrNi40 schwierig oder unmöglich ist, eine sich über den gesamten Querschnitt des Formteils erstreckende Legierungszone zu erhalten. Die Legierungszone erfasst vielmehr, wie Figur 6 der EP 1 416 599 A2 offenbart, nur den Randbereich des Formteils, wo sie eine ausladende Schweißwulst bildet, welche Fußpunkt unerwünschter Funkenüberschläge werden kann.However, there remains the disadvantage that it is difficult or impossible, both over the entire cross-section, both when welding the thin disk of IrNi40 to the Inconel 600 and when welding the molding of the nobler iridium or platinum alloy onto the thin disk of IrNi40 To obtain the molding of extending alloy zone. The alloying zone rather, like FIG. 6, detects the EP 1 416 599 A2 discloses only the edge region of the molding, where it forms a bulging weld bead, which may become the base of undesired flashovers.

Die EP 1 376 791 A1 offenbart, zwischen der unedlen Masseelektrode und dem edlen Formteil, mit welchem die Masseelektrode bestückt werden soll, ein Zwischenstück - insbesondere aus einer Edelmetalllegierung - vorzusehen, dessen linearer Ausdehnungskoeffizient weder mit dem der Masseelektrode noch mit dem des edlen Formteils übereinstimmt, sondern dazwischen liegt.The EP 1 376 791 A1 discloses between the non-noble ground electrode and the noble molding, with which the ground electrode is to be equipped, an intermediate piece - in particular of a noble metal alloy - provide, the linear expansion coefficient of which neither matches the ground electrode with that of the noble molding, but intervenes.

Eine Zündkerze mit den im Oberbegriff des Anspruchs 1 angegebenen Merkmalen offenbart die JP 2005-203110 A . Danach ist es bekannt, ein vorgefertigtes nietförmiges Verbundteil, welches aus einem Edelmetallformteil und einem Zwischenstück besteht, welches aus dem gleichen Unedelmetallwerkstoff wie die Masseelektrode besteht, stumpf auf die Masseelektrode zu schweißen.A spark plug with the features specified in the preamble of claim 1 discloses the JP 2005-203110 A , Thereafter, it is known, a prefabricated rivet-shaped Composite part, which consists of a precious metal molding and an intermediate piece, which consists of the same base metal material as the ground electrode to weld butt to the ground electrode.

In der JP 2004-186152 A ist eine nicht gattungsgemäße Zündkerze offenbart, deren Masseelektrode mit einem Sackloch versehen ist, in welches ein Edelmetallformteil eingesetzt und mit der Masseelektrode verschweißt ist.In the JP 2004-186152 A a non-generic spark plug is disclosed, the ground electrode is provided with a blind hole, in which a precious metal molded part is inserted and welded to the ground electrode.

EP1341282 offenbart den Oberbegriff der Ansprüche 1 und 4. Der vorliegenden Erfindung liegt die Aufgabe zugrunde, einen Weg aufzuzeigen, wie die Lebensdauer einer gattungsgemäßen Zündkerze verlängert werden kann. EP1341282 discloses the preamble of claims 1 and 4. The present invention has for its object to provide a way how the life of a generic spark plug can be extended.

Diese Aufgabe wird gelöst durch eine Zündkerze mit den im Anspruch 1 angegebenen Merkmalen und durch ein Verfahren zu ihrer Herstellung mit den im Anspruch 4 angegebenen Merkmalen. Vorteilhafte Weiterbildungen der Erfindung sind Gegenstand der Unteransprüche.This object is achieved by a spark plug having the features specified in claim 1 and by a method for their preparation with the features specified in claim 4. Advantageous developments of the invention are the subject of the dependent claims.

Bei einer erfindungsgemäßen Zündkerze hat das Zwischenstück einen thermischen Ausdehnungskoeffizienten, der nicht von dem thermischen Ausdehnungskoeffizienten der unedlen Masseelektrode abweicht. Am besten besteht das Zwischenstück aus demselben Werkstoff wie die unedle Masseelektrode. Das aus dem Formteil und dem Zwischenstück gebildete Verbundteil steckt so in einem durchgehenden Loch der Masseelektrode, dass es bündig mit der der Mittelelektrode zugewandten Oberfläche der Masseelektrode abschließt. Das hat wesentliche Vorteile:

  • Das Zwischenstück passt bestmöglich zum Material der Masseelektrode, was für das Verschweißen des Zwischenstücks mit der Masseelektrode optimal ist.
  • In der Verbindungszone zwischen der Masseelektrode und dem Zwischenstück treten keine Wärmespannungen auf. Deshalb ist ein Ablösen des Zwischenstückes von der Masseelektrode selbst dann nicht zu befürchten, wenn sich die Schweißzone nicht auf den gesamten Querschnitt des Zwischenstücks erstreckt, sondern nur auf den Randbereich.
  • Das Formteil aus einem Edelmetall oder aus einer Edelmetalllegierung kann auf das Zwischenstück geschweißt werden, bevor das Zwischenstück mit der unedlen Masseelektrode verschweißt wird. Einschränkungen, wie sie beim Aufschweißen des Zwischenstücks auf die Masseelektrode auftreten würden, treten nicht auf, wenn das Formteil und das Zwischenstück miteinander verschweißt werden, bevor das Zwischenstück mit der Masseelektrode verschweißt wird, vielmehr ist die Verbindungszone zwischen dem Formteil und dem Zwischenstück von allen Seiten her bestens zugänglich, so dass eine sich über den gesamten Querschnitt erstreckende Legierungszone aus dem Werkstoff des Formteils und aus dem Werkstoff des Zwischenstücks gebildet werden kann. In der Legierungszone gibt es einen stetigen Übergang vom niedrigeren Wärmeausdehnungskoeffizienten des Edelmetallwerkstoffs zum höheren Wärmeausdehnungskoeffizienten des unedlen Werkstoffs des Zwischenstückes. Zusammengenommen setzen diese beiden Maßnahmen das Risiko einer Rissbildung in der Legierungszone drastisch herab.
  • Durch das Aufbringen des Edelmetall-Formteils auf das unedle Zwischenstück als Sockel kann der Spannungsbedarf für die Erzeugung der Zündfunken herabgesetzt werden. Das führt in weiterer Folge in Verbindung mit dem Einbetten des Edelmetallformteils in die unedle Masseelektrode, so dass das Formteil bündig mit der Oberfläche der unedlen Masseelektrode abschließt, zu einem geringeren Abbrand, zu einer erhöhten Lebensdauer und auch zu verbesserten Kaltstarteigenschaften, weil bei verschmutzten Zündkerzen der parasitäre Anteil beim Spannungsanstieg infolge des geringeren Spannungsbedarfes herabgesetzt wird.
In a spark plug according to the invention, the intermediate piece has a thermal expansion coefficient which does not deviate from the thermal expansion coefficient of the base ground electrode. The intermediate piece is best made of the same material as the base earth electrode. The composite part formed from the molded part and the intermediate piece inserted in a through hole of the ground electrode so that it is flush with the surface of the ground electrode facing the center electrode. This has significant advantages:
  • The adapter fits best possible to the material of the ground electrode, which is optimal for welding the intermediate piece with the ground electrode.
  • In the connection zone between the ground electrode and the intermediate piece, no thermal stresses occur. Therefore, a detachment of the intermediate piece from the ground electrode is not to be feared even if the welding zone does not extend to the entire cross section of the intermediate piece, but only to the edge region.
  • The molded article made of a noble metal or a noble metal alloy can be welded onto the intermediate piece before the intermediate piece is welded to the base ground electrode. Restrictions, such as when welding of the intermediate piece on the ground electrode, do not occur when the molded part and the intermediate piece are welded together before the intermediate piece is welded to the ground electrode, but the connection zone between the molding and the intermediate piece is easily accessible from all sides, so that an alloying zone extending over the entire cross-section can be formed from the material of the molded part and from the material of the intermediate piece. In the alloying zone there is a steady transition from the lower coefficient of thermal expansion of the noble metal material to the higher coefficient of thermal expansion of the base non-precious material. Taken together, these two measures drastically reduce the risk of cracking in the alloy zone.
  • By applying the precious metal molding on the base base as a base, the voltage requirement for the generation of the spark can be reduced. This leads in consequence in connection with the embedding of the noble metal molded part in the non-noble ground electrode, so that the molded part flush with the surface of the base ground electrode, to a lower burnup, increased life and also to improved cold start, because with soiled spark plugs parasitic component is reduced in the voltage increase due to the lower voltage requirement.

Als Werkstoff für die unedle Masseelektrode und auch für das Zwischenstück eignen sich hochwärmebeständige Nickelbasislegierungen besonders, z. B. Inconelwerkstoffe, insbesondere Inconel 600. Andere gut geeignete Legierungen sind Nickelbasislegierungen, welche 1,5 bis 2,5 Gew.-% Silizium, 1,5 bis 3 Gew.-% Aluminium, bis zu 0,5 Gew.-% Mangan und 0,05 bis 0,2 Gew.-% Titan in Kombination mit 0,1 bis 0,3 Gew.-% Zirkon enthalten und zum Rest aus Nickel bestehen, wobei das Zirkon ganz oder teilweise durch die doppelte Masse Hafnium ersetzt sein kann. Eine andere gut geeignete Nickelbasislegierung enthält 1,5 bis 2,5 Gew.-% Silizium, 1,5 bis 3 Gew.-% Aluminium, bis zu 0,5 Gew.-% Mangan und 0,005 bis 0,2 Gew.-% Yttrium in Kombination mit 0,05 bis 0,3 Gew.-% Lanthan und als Rest Nickel.As a material for the non-noble ground electrode and also for the intermediate piece are highly heat-resistant nickel-based alloys particularly, z. Inconel materials, in particular Inconel 600. Other well-suited alloys are nickel-based alloys containing 1.5 to 2.5% by weight of silicon, 1.5 to 3% by weight of aluminum, up to 0.5% by weight of manganese and 0.05 to 0.2 wt .-% of titanium in combination with 0.1 to 0.3 wt .-% zirconium and the remainder of nickel, wherein the zirconium may be wholly or partially replaced by the double mass hafnium , Another suitable nickel-base alloy contains 1.5 to 2.5% by weight of silicon, 1.5 to 3% by weight of aluminum, up to 0.5% by weight of manganese and 0.005 to 0.2% by weight. Yttrium in combination with 0.05 to 0.3 wt .-% lanthanum and the balance nickel.

Als Edelmetallwerkstoffe für das Formteil eignen sich besonders Platin, Iridium und deren Basislegierungen. Für Platinbasislegierungen kommen vor allem Iridium, Rhodium, Ruthenium, Palladium, Wolfram, Nickel und Osmium als Legierungsbestandteile in Betracht. Für Iridiumbasislegierungen kommen vor allem Platin, Rhodium, Palladium, Rhenium und Chrom als Legierungsbestandteile in Betracht. Besonders geeignet sind Iridium-Rhodiumlegierungen, insbesondere Iridium mit 10 Gew.-% Rhodium. Darüber hinaus können die Edelmetallwerkstoffe für das Formteil noch geringe Mengen Oxide eines oder mehrerer der Elemente Zirkon, Yttrium, Hafnium, Cer, Titan, Magnesium, Barium und Lanthan enthalten, zusammengenommen vorzugsweise 0,05 bis 1 Gew.-%. Das Zwischenstück bzw. ein aus dem unedlen Zwischenstück und dem edlen Formteil gebildetes Verbundteil kann auf unterschiedliche Weise mit der Masseelektrode verbunden werden. Eine Möglichkeit besteht darin, in der unedlen Masseelektrode ein durchgehendes Loch vorzusehen und das aus dem Formteil und dem Zwischenstück gebildete Verbundteil so in die durchgehende Bohrung einzusetzen, dass das Zwischenstück an der der Mittelelektrode abgewandten Seite der Masseelektrode mit dieser verschweißt werden kann. Das kann dadurch erleichtert werden, dass das Verbundteil nach Art eines Nietes mit einem Kopf versehen ist, welcher sich an dem Zwischenstück befindet und an der Masseelektrode anschlägt, wenn das Verbundteil in das Loch der Masseelektrode gesteckt wird. Das edelmetallhaltige Formteil soll bündig mit der der Mittelelektrode zugewandten Oberfläche der Masseelektrode abschließen.As noble metal materials for the molding are particularly suitable platinum, iridium and their base alloys. For platinum-based alloys are mainly iridium, rhodium, ruthenium, palladium, tungsten, nickel and osmium as alloying components into consideration. For iridium-based alloys are mainly platinum, rhodium, palladium, rhenium and chromium as alloying components into consideration. Particularly suitable are iridium-rhodium alloys, in particular iridium with 10 wt .-% rhodium. In addition, the noble metal materials for the molding may contain small amounts of oxides of one or more of the elements zirconium, yttrium, hafnium, cerium, titanium, magnesium, barium and lanthanum, taken together preferably 0.05 to 1 wt .-%. The intermediate piece or a composite part formed from the non-precious intermediate piece and the noble molded part can be connected to the ground electrode in different ways. One possibility is to provide a continuous hole in the base ground electrode and to insert the composite part formed from the shaped part and the intermediate piece into the through hole in such a way that the intermediate piece can be welded thereto at the side facing away from the center electrode of the ground electrode. This can be facilitated by providing the composite part with a head in the manner of a rivet, which is located at the intermediate piece and abuts against the ground electrode when the composite part is inserted into the hole of the ground electrode. The precious metal-containing molded part should terminate flush with the center electrode facing surface of the ground electrode.

Gegenstand des Anspruchs 4 ist ein Verfahren zum Armieren einer Masseelektrode für eine Zündkerze mit den Merkmalen des Anspruchs 1.The subject matter of claim 4 is a method for reinforcing a ground electrode for a spark plug having the features of claim 1.

Beim Herstellen einer solchen Zündkerze wird das edelmetallhaltige Formteil, mit welchem die Masseelektrode armiert werden soll, auf ein Zwischenstück aus einem Werkstoff geschweißt, dessen thermischer Ausdehnungskoeffizient nicht vom thermischen Ausdehnungskoeffizienten der unedlen Masseelektrode abweicht. Das aus dem Formteil und dem Zwischenstück gebildete Verbundteil wird anschließend so in das durchgehende Loch der Masseelektrode gesteckt, dass das Formteil mit der der Mittelelektrode zugewandten Oberfläche der Masseelektrode bündig abschließt, und wird mit der unedlen Masseelektrode verschweißt. Die Schweißverbindung erfolgt auf der der Mittelelektrode abgewandten Seite der Masseelektrode und zwar am besten durch Laserschweißen.When producing such a spark plug, the noble metal-containing molded part, with which the ground electrode is to be reinforced, welded to an intermediate piece of a material whose thermal expansion coefficient does not deviate from the thermal expansion coefficient of the base ground electrode. The composite part formed from the molded part and the intermediate piece is then inserted into the through hole of the ground electrode so that the molded part is flush with the surface of the ground electrode facing the center electrode, and is welded to the base ground electrode. The welded connection takes place on the center electrode opposite side of the ground electrode, and preferably by laser welding.

Die Masseelektrode besteht üblicherweise aus einem Profildraht mit einem Rechteckprofil, von welchem ein gerader Abschnitt abgetrennt und mit dem Körper der Zündkerze verschweißt wird. Erst danach wird die Masseelektrode zur Mittelelektrode hin gebogen. Das Verbundteil, mit welchem die Masseelektrode armiert werden soll, wird mit der Masseelektrode vorzugsweise verschweißt, solange wie die Masseelektrode noch nicht zur Mittelelektrode hin gebogen ist, sondern noch gerade verläuft. Das erleichtert das Verschweißen des Verbundteils mit der Masseelektrode beträchtlich.The ground electrode usually consists of a profile wire with a rectangular profile, from which a straight section is separated and welded to the body of the spark plug. Only then is the ground electrode bent towards the center electrode. The composite part, with which the ground electrode is to be reinforced, is preferably welded to the ground electrode as long as the ground electrode is not yet bent towards the center electrode, but is still straight. This considerably facilitates the welding of the composite part to the ground electrode.

Vorzugsweise werden das Formteil und das Zwischenstück zunächst vorläufig miteinander verbunden und anschließend mittels eines Lasers verschweißt. Das vorläufige Verbinden kann dadurch geschehen, dass sie durch elektrisches Widerstandsschweißen stumpf miteinander verschweißt werden. Eine andere Möglichkeit besteht darin, das Formteil und das Zwischenstück durch Kaltverschweißen stumpf miteinander zu verbinden, z. B. durch Reibschweißen oder durch Zusammenpressen unter gleichzeitiger Durchmesservergrößerung durch Stauchen. Das elektrische Widerstandsschweißen und das Kaltverschweißen sind als Verfahren zum Herstellen von Bimetallkontaktnieten an sich bekannt.Preferably, the molded part and the intermediate piece are first provisionally connected to each other and then welded by means of a laser. Preliminary bonding can be accomplished by butting them together by electrical resistance welding. Another possibility is to butt the molded part and the intermediate piece by cold welding, for. B. by friction welding or by compression with simultaneous increase in diameter by upsetting. Electrical resistance welding and cold welding are known per se as a method of making bimetallic contact rivets.

Ist durch vorläufiges Verbinden des Formteils mit dem Zwischenstück ein Verbundteil gebildet, kann deren Verbindungszone durch Laserschweißen so bearbeitet werden, dass sich eine Legierungszone ausbildet, welche sich über den gesamten Querschnitt des Verbundteils erstreckt. Dazu wird das Verbundteil zweckmäßigerweise um seine eigene Längsachse gedreht, während sich seine Verbindungszone im Einwirkungsbereich des Laserstrahls befindet und rundum vom Laserstrahl getroffen wird.If a composite part is formed by provisionally connecting the molded part to the intermediate piece, its connecting zone can be processed by laser welding in such a way that an alloy zone is formed which extends over the entire cross section of the composite part. For this purpose, the composite part is expediently rotated about its own longitudinal axis, while its connection zone is located in the area of action of the laser beam and is hit all around by the laser beam.

Das Formteil und das Zwischenstück können von einem drahtförmigen Halbzeug abgeschnitten und dann miteinander verbunden werden. Es ist aber auch möglich, zwei drahtförmige Halbzeuge zunächst an ihren Enden vorläufig miteinander zu verbinden und sie erst dann vom jeweiligen Halbzeug abzuschneiden und ergänzend mit einem Laser zu verschweißen. Schließlich ist es möglich, ein vom Halbzeug abgeschnittenes, überwiegend aus Edelmetall bestehendes Formteil vorläufig mit dem Ende eines unedlen drahtförmigen Halbzeugs zu verbinden und erst danach das Verbundteil vom unedlen Halbzeug zu trennen. Die zuletzt genannte Vorgehensweise wird bevorzugt.The molded part and the intermediate piece can be cut off from a wire-shaped semifinished product and then joined together. But it is also possible to provisionally connect two wire-shaped semi-finished products at their ends first and then cut them from the respective semifinished product and to weld additionally with a laser. Finally, it is possible, a cut off from the semi-finished, consisting mainly of precious metal molding provisionally with the end of a base wire-shaped semifinished product to connect and only then to separate the composite part of non-precious semi-finished product. The latter approach is preferred.

Anstelle des Laserschweißens kann auch ein Elektronenstrahlschweißen stattfinden.Instead of laser welding and electron beam welding can take place.

Der weiteren Erläuterung der Erfindung dienen die beigefügten Zeichnungen. Darin zeigen

  • Figur 1 die Spitze einer nicht erfindungsgemäßen Zündkerze in einer Schrägansicht,
  • Figur 2 verschiedene Schritte beim Armieren einer Masseelektrode einer Zündkerze und
  • Figur 2a ein Beispiel der Armierung einer Masseelektrode.
For further explanation of the invention serve the accompanying drawings. Show in it
  • FIG. 1 the tip of a spark plug not according to the invention in an oblique view,
  • FIG. 2 various steps in arming a ground electrode of a spark plug and
  • FIG. 2a an example of the reinforcement of a ground electrode.

Gleiche oder einander entsprechende Teile sind in den Beispielen mit übereinstimmenden Bezugszahlen bezeichnet.Like or corresponding parts are designated in the examples with corresponding reference numerals.

Figur 1 zeigt eine Zündkerze mit einem Zündkerzenkörper 1 aus einer hochwärmebeständigen Legierung, z. B. aus einer Nickelbasislegierung. Im Körper 1 ist ein keramischer Isolator 2 angeordnet, in welchen eine Mitteelektrode 3 eingebettet ist, welche aus Kupfer bestehen kann und mit einer Edelmetallspitze 5 armiert ist, welche auf das vordere Ende der Mittelelektrode 3 unter Bildung einer Verbindungszone 7 aufgeschweißt ist, in welcher eine Legierung aus den Bestandteilen der Werkstoffe für die Mittelelektrode 3 und der Edelmetallspitze 5 vorliegt. FIG. 1 shows a spark plug with a spark plug body 1 made of a highly heat-resistant alloy, for. B. of a nickel-based alloy. In the body 1, a ceramic insulator 2 is disposed, in which a center electrode 3 is embedded, which may be made of copper and is reinforced with a noble metal tip 5, which is welded to the front end of the center electrode 3 to form a connection zone 7, in which a Alloy of the constituents of the materials for the center electrode 3 and the noble metal tip 5 is present.

Auf den vorderen Rand des Körpers 1 ist eine Masseelektrode 4 geschweißt, welche üblicherweise aus einer Nickellegierung besteht. Die Masselelektrode 4 ist aus einem Profildraht mit rechteckigem Querschnitt gebildet und als Dachelektrode ausgebildet, d. h., sie ist rechtwinklig umgebogen, so dass ihr umgebogener Abschnitt der Edelmetallspitze 5 der Mittelelektrode 3 gegenüberliegt. Die Masseelektrode 4 ist mit einem überwiegend aus Edelmetall bestehenden Formteil 6 armiert, welches auf einen Sockel 9 geschweißt ist, der als Zwischenstück zwischen der Masseelektrode 4 und dem überwiegend aus Edelmetall bestehenden Formteil 6 dient, welches unter Ausbildung einer den ganzen Querschnitt des Sockels 9 erfassenden Verbindungszone 8 mit dem Sockel 9 verschweißt ist. In der Verbindungszone 8 liegt eine Legierung aus den Bestandteilen der Werkstoffe vor, aus welchen das Zwischenstück 9 (der Sockel) und das Formteil 6 bestehen. Die Edelmetallspitze 5 und das aus Edelmetall gebildete Formteil 6 liegen einander in vorbestimmtem Abstand gegenüber.On the front edge of the body 1, a ground electrode 4 is welded, which usually consists of a nickel alloy. The ground electrode 4 is formed from a profile wire having a rectangular cross-section and formed as a roof electrode, that is, it is bent at right angles, so that its bent portion of the noble metal tip 5 of the center electrode 3 is opposite. The ground electrode 4 is reinforced with a predominantly made of precious metal molded part 6, which is welded to a base 9, which serves as an intermediate piece between the ground electrode 4 and the predominantly made of precious metal molding 6, which forms a the entire cross section of the base 9 detecting connecting zone 8 is welded to the base 9. In the connection zone 8 is an alloy of the constituents of the materials from which the intermediate piece 9 (the base) and the molded part 6 exist. The noble metal tip 5 and the molded part 6 formed of noble metal face each other at a predetermined distance.

Zum Armieren der Masseelektrode 4 geht man vorzugsweise so vor, wie es in Figur 2 dargestellt ist: Auf das stumpfe Ende eines drahtförmigen Halbzeugs 10, aus welchem das unedle Zwischenstück 9 gebildet wird, wird durch elektrisches Widerstandsschweißen ein Formteil 6 geschweißt. Das Formteil 6 ist ein Abschnitt von einem überwiegend aus Edelmetall bestehenden drahtförmigen Halbzeug, dessen Durchmesser etwas kleiner ist als der des Halbzeuges 10. Nachdem das Formteil 6 mit dem Ende des drahtförmigen Halbzeuges 10 vorläufig verschweißt ist, wird die Verbindungszone 8 zwischen ihnen mit einem Laser bearbeitet, welcher um die Verbindungszone 8 herumgeführt wird. Alternativ kann der Verbund aus dem Halbzeug 10 und dem Formteil 6 um seine Längsachse 11 gedreht werden, wobei der Laser stationär auf die Verbindungszone 8 gerichtet bleibt. Durch das Laserschweißen wird in der Verbindungszone 8 eine Legierung ausgebildet, welche aus den Bestandteilen der Werkstoffe der beteiligten Drahtabschnitte besteht und sich über den gesamten Querschnitt des Formteils 6 und des Zwischenstücks 9 erstreckt. Anschließend wird ein Verbundteil 12, welches aus dem Formteil 6, der Verbindungszone 8 und einem Zwischenstück 9 aus dem Halbzeug 10 besteht, vom Halbzeug 10 abgetrennt und mit der Masseelektrode 4 verschweißt.For arming the ground electrode 4, it is preferable to proceed as in FIG. 2 On the blunt end of a wire-shaped semifinished product 10, from which the base intermediate piece 9 is formed, a molded part 6 is welded by electrical resistance welding. The molded part 6 is a section of a predominantly made of precious metal wire-shaped semifinished product whose diameter is slightly smaller than that of the semifinished product 10. After the molding 6 is temporarily welded to the end of the wire-shaped semifinished product 10, the connection zone 8 between them with a laser processed, which is led around the connection zone 8. Alternatively, the composite of the semifinished product 10 and the molded part 6 can be rotated about its longitudinal axis 11, wherein the laser remains stationary directed to the connection zone 8. By laser welding, an alloy is formed in the connection zone 8, which consists of the constituents of the materials of the wire sections involved and extends over the entire cross section of the molded part 6 and the intermediate piece 9. Subsequently, a composite part 12, which consists of the molded part 6, the connection zone 8 and an intermediate piece 9 of the semifinished product 10, separated from the semifinished product 10 and welded to the ground electrode 4.

Figur 2a zeigt eine Möglichkeit, die Masseelektrode 4 zu armieren, nämlich mittels eines Verbundteils 12, dessen Zwischenstück 9 mit einem Kopf 9a versehen ist, welcher durch Stauchen gebildet sein kann. Ein solches Verbundteil 12 wird von hinten her in ein durchgehendes Loch 14 der Masseelektrode 4 gesteckt und mit ihr an der der Mittelelektrode 3 abgewandten Seite der Masseelektrode 4 verschweißt, dort, wo der Kopf 9a an der Masseelektrode 4 anschlägt. In diesem Fall kann das Verschweißen allein durch Laserschweißen erfolgen. An der der Mittelelektrode 3 zugewandten Seite schließt das Formteil 6 bündig mit der Oberfläche der Masseelektrode 4 ab. FIG. 2a shows a way to arm the ground electrode 4, namely by means of a composite part 12, the intermediate piece 9 is provided with a head 9a, which may be formed by upsetting. Such a composite part 12 is inserted from behind into a through hole 14 of the ground electrode 4 and welded to it at the side facing away from the center electrode 3 of the ground electrode 4, where the head 9a abuts against the ground electrode 4. In this case, the welding can be done by laser welding alone. At the side facing the center electrode 3, the molded part 6 is flush with the surface of the ground electrode 4.

Bezugszahlenliste:LIST OF REFERENCE NUMBERS:

1.1.
Körper der ZündkerzeBody of the spark plug
2.Second
Isolatorinsulator
3.Third
Mittelelektrodecenter electrode
4.4th
Masseelektrodeground electrode
5.5th
Edelmetallspitzenoble metal tip
6.6th
Formteilmolding
7.7th
Verbindungszoneconnecting zone
8.8th.
Verbindungszoneconnecting zone
9.9th
Zwischenstück, als Sockel ausgebildetAdapter, designed as a base
9a.9a.
Kopfhead
10.10th
HalbzeugWorkpiece
11.11th
Längsachselongitudinal axis
12.12th
Verbundteilcomposite part
14.14th
durchgehendes Lochthrough hole

Claims (10)

  1. Spark plug
    - having a body (1) made of a non-noble metal material in which an insulator (2) is arranged,
    - having a central electrode (3) arranged in the insulator (2),
    - having a ground electrode (4) that proceeds from the body (1) and to which is welded a molded part (6) that faces the central electrode (3) and the mass of which primarily consists of one or a plurality of noble metals, and,
    - having an intermediate piece (9) that is provided between the molded part (6) and the ground electrode (4) and that is welded to the molded part (6) and to the ground electrode (4),
    wherein a composite part (12) formed from the molded part (6) and the intermediate piece (9) is inserted in a hole (14) of the non-noble ground electrode (4) and passes through the ground electrode (4), and
    wherein the intermediate piece (9) is welded to the ground electrode (4) at the side thereof that faces away from the central electrode (3),
    characterized in that the intermediate piece (9) consists of the same material as the non-noble ground electrode (4), and,
    in that the molded part (6) closes in a flush manner with the surface of the ground electrode (4) facing the central electrode (3).
  2. The spark plug according to claim 1, characterized in that the molded part (6) consists of platinum
    or of a platinum-based alloy that contains one or a plurality of the components iridium, rhodium, ruthenium, palladium, tungsten, nickel, and osmium,
    or consists of iridium
    or of an iridium-based alloy that contains one or a plurality of the following components: rhodium, platinum, nickel, chromium, palladium, rhenium.
  3. The spark plug according to any of the foregoing claims, characterized in that the molded part contains an oxide of one or a plurality of the elements zirconium, yttrium, hafnium, cerium, titanium, magnesium, barium, lanthanum.
  4. The method for reinforcing a ground electrode (4) of a spark plug according to any of the foregoing claims having a molded part (6), the mass of which primarily consists of one or a plurality of noble metals, in that the molded part (6) is welded onto an intermediate piece (9),
    wherein a through-hole (14) is provided in the non-noble ground electrode (4), wherein the composite part (12) formed from the molded part (6) and the intermediate piece (9) is inserted into the through-hole (14), and,
    wherein the intermediate piece (9) is welded to the non-noble ground electrode (4) at the side thereof that faces away from the central electrode (3), characterized in that the intermediate piece (9) consists of the same material as the non-noble ground electrode (4), and,
    in that the composite part (12) formed from the molded part (6) and the intermediate piece (9) is inserted into the through-hole (14) such that the composite part (12) closes in a flush manner with the surface of the ground electrode (4) facing the central electrode (3).
  5. The method in accordance with claim 4, characterized in that the molded part (6) and the intermediate piece (9) are first temporarily connected to one another and then are welded to one another using a laser or electron beam welding.
  6. The method in accordance with claim 5, characterized in that the molded part (6) and the intermediate piece (9) are rotated about their common center longitudinal axis (11) and during this are welded with the laser.
  7. The method in accordance with claim 5 or 6, characterized in that the molded part (6) and the intermediate piece (9) are temporarily connected to one another using resistance welding or using cold welding.
  8. The method in accordance with any one of claims 4 through 7, characterized in that wire segments are used as molded part (6) and as intermediate piece (9).
  9. The method in accordance with claim 8, characterized in that the molded part (6) and a wire from which the intermediate piece (9) is formed are temporarily butt welded to one another,
    a composite part (12) formed thereby is separated from the wire supply and then the connection zone (8) between the molded part (6) and the wire for forming an alloy extending across the entire cross-section is additionally welded with a laser or using electron beam welding.
  10. The method in accordance with claim 8, characterized in that the molded part (6) and a wire from which the intermediate piece (9) is formed are temporarily butt welded to one another, then the connection zone (8) between the molded part (6) and the wire for forming an alloy extending across the entire cross-section is additionally welded with a laser or using electron beam welding and then a composite part (12) formed thereby is separated from the wire supply.
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DE102010027463B4 (en) 2010-07-17 2016-12-22 Federal-Mogul Ignition Gmbh Spark plug and method for its production
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