Classifications

• • 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

Definitions

• Spark plug electrode made of improved electrode material
• the invention relates to a spark plug electrode made of a nickel-base electrode material.
• Spark plug electrodes are exposed to high loads.
• an ignition system controlled by the engine periodically generates a high voltage, which discharges in a flashover between the two electrodes of the spark plugs. The generated spark then ignites the compressed air-fuel mixture.
• the spark plug is subject to a continuous load due to extremely high temperatures. So that the engine power in continuous operation does not decrease due to leaking, poorly ignited or hot-runned spark plugs, the materials for the production of spark plug electrodes for internal combustion engines, a permanent further development.
• nickel alloys are usually used because nickel has both a high melting temperature, which is indispensable for the temperature resistance of the alloy, as well as a high resistance to corrosion.
• materials made of pure precious metals or based on precious metals, such as platinum or platinum alloys with iridium in terms of wear resistance to spark erosive attacks increased durability and thus very high lifetimes of the electrodes, but provide
• Spark plug electrode materials made of platinum in view of the enormous cost, for economic reasons is not a suitable alternative to commercial nickel alloys.
• the resistance of nickel alloys manifests itself in low erosion losses, ie the removal of material from the electrode, induced by the interaction of the arc with the electrode surface, and in a high oxidation and corrosion resistance.
• the corrosion resistance can by metallic additives such as aluminum, manganese, chromium and be further increased. Addition of silicon to the nickel-base alloy further increases the high-temperature oxidation resistance.
• a nickel-based alloy for use for spark plug electrodes for internal combustion engines which consists essentially of nickel, silicon, manganese and
• Chromium may contain up to 2% by weight, or Y or a rare earth element of up to 0.5% by weight, as further constituents. According to the statements of this document nickel alloys are obtained, the good because of their strength at elevated temperatures
• Oxidation and corrosion resistance and increased resistance to spark erosion have.
• the spark plug electrode according to the invention with the features of the main claim is characterized by an extremely high temperature resistance compared to known electrode materials based on nickel alloys, a minimized spark erosive wear or electrode erosion and has a unique oxidation and corrosion resistance.
• This provides a low cost electrode material for spark plug electrodes that allows for life previously only achieved for noble metal and precious metal alloy electrode materials.
• This is inventively achieved in that the spark plug electrode is made of an electrode material containing nickel as a base material, and further 0.5 to 3 At. -% (atomic%) silicon and at least 6 At. - contains% aluminum.
• the spark plug electrode according to the invention has an optimized with respect to the chemical and physical properties alloy.
• the combination of nickel, silicon and aluminum in the specified amounts means that the alloy is both simple and lossless to produce, as well as, due to its homogeneity, has a long-lasting good application profile.
• the extreme temperature resistance of the spark plug electrode according to the invention which manifests itself in an excellent spark erosion resistance and oxidation and corrosion resistance even in continuous operation of the spark plug.
• spark plug electrode according to the invention has an improved thermal conductivity compared to the known materials.
• Electrode material with other reactive elements the spark erosive wear can be reduced even more significantly and an increase in the oxidation and corrosion resistance is made possible.
• the sum of the advantages of the spark plug electrode according to the invention leads to particularly long replacement intervals of the spark plugs and to increased acceptance by the market due to the achievable long service life.
• the invention relates to a spark plug electrode made of an electrode material comprising nickel, 0.5 to 3 at. -% silicon and at least 6 At. - contains% aluminum.
• an electrode material comprising nickel, 0.5 to 3 at. -% silicon and at least 6 At. - contains% aluminum.
• an electrode material has advantages in terms of oxidation and corrosion resistance, as well as an excellent resistance to spark erosive wear.
• spark erosive wear When igniting a spark between the center and the ground electrode of a spark plug, the material is worn by oxidation processes or by the melting or flaking of near-surface material areas on the two surfaces of the electrodes by the high temperatures in the arc. This is called spark erosive wear.
• This delamination or blow-off of electrode material is counteracted in the prior art by admixtures of aluminum and silicon to the nickel-based alloy. It can be seen that the maximum amount of silicon to be incorporated in a range of about 1.5 to 3 Wt .-% and the maximum amount of aluminum, which
• the high content of aluminum as a whole means that its content is also increased at the surface of the electrode material.
• the high content of aluminum atoms on the electrode surface uniformly distributed alumina areas that show excellent and compared to nickel oxide much greater resistance to spark erosion wear.
• the nickel-based alloy Due to the high doping of the nickel-based alloy with aluminum, in the case of flaking of the aluminum oxide particles from the interior of the alloy, further aluminum can be replenished to the surface of the electrode material, which in turn forms a resistant oxide layer. Thus, the nickel base material is spared and subject to a significantly reduced degradation.
• spark erosive wear is significantly reduced compared to the spark plug electrode material according to the invention.
• the silicon serves to improve high temperature corrosion and oxidation resistance.
• Silicon is chemically nonmetallic and has a relatively high melting point. As a result, it stabilizes the alloy, especially at high temperatures. Due to its proximity to the semi-metals, it also shows semiconductor-like physical properties. These are essential for its good processibility in metallic alloys. In particular, this is important for the electrode material according to the invention, since thus also the relatively high proportion of up to about 3 At. -% silicon can be homogeneously incorporated into the alloy material. While it has hitherto been difficult to provide such high silicon contents in nickel-base alloys, this is achieved with the composition of the electrode material according to the invention, whereby the excellent temperature resistance is achieved.
• the electrode material for spark plug electrodes according to the invention also has an improved thermal conductivity compared to conventional electrode materials. Without being bound by theory, it is believed that this is due to the extraordinary homogeneity of the composition of the electrode material. Due to the increased thermal conductivity, the maximum electrode temperature is lower, whereby the corrosive attack is less pronounced.
• spark plugs can be produced, with which service lives are achieved in about the same range as those for noble metal material spark plugs. Whereas, however, the service life of conventional spark plugs is only about 60,000 km, the service lives of the spark plug electrodes according to the invention are a good half higher, ie more than 90,000 km. This creates a much better acceptance in the market and is beneficial for environmental as well as for business reasons.
• spark erosion experiments were carried out.
• the electrode material was placed in a suitable holder between a light source and a receiving screen, and a shadow image was taken in the raw state. Subsequently, a spark was generated several times between the electrode surfaces. After reaching a predefined number of ignitions, another silhouette was finally taken. Both silhouettes became together compared. The spark erosive Versch prolong was recognizable by material removal. The quotient of the surface wear and the number of sparks thus provided a measure of the resistance of the tested electrode material to spark erosion.
• Spark plug electrode in addition to the nickel-based alloy about 0.5 to 2 At. -% silicon and about 6 to 30 at. -% aluminum. Just such a ratio has been shown to be particularly easy to process. Proportions of about 6 to 30 at. % Of aluminum is sufficient for a homogeneous distribution of aluminum in the alloy material and requires the formation of finely divided dense but thin alumina areas on the surface of the electrode material, thereby providing excellent oxidation and corrosion resistance and minimizing spark erosion of the electrode.
• the proportion of 0.5 to 2 At. -% silicon is particularly advantageous in terms of the homogeneous processability of the silicon on the one hand and also the excellent increase in the temperature resistance of the electrode material.
• the proportion of aluminum between about 7 and 10 at. -% lies. It has been shown that in a range over 10 At. -% aluminum in the alloy, the oxidation and corrosion resistance can not be increased to a proportional extent, such as below 15 At. -% the case is. For economic reasons, therefore, an electrode material according to the invention is to be preferred, the aluminum in a range between about 7 and 10 At. - contains%. This amount is sufficient to provide on the surface of the nickel alloy a blanket thin layer of alumina for increasing the oxidation and corrosion resistance, as well as the spark erosion resistance, and further to demand aluminum from the interior of the electrode material to the surface of the electrode as needed. Below 7 At. -% to at least 6 At. -% can still be formed sufficient alumina, while still further reduced amounts can increase the wear of the electrode material again, since the aluminum oxide protective layer is not formed on the surface of the electrode surface.
• the spark plug electrode may also contain in its alloy material reactive elements, individually or in any desired combination.
• reactive elements elements of the periodic table of the elements are referred to, which can be found in particular under the subgroup elements of the fifth and sixth period as well as the lanthanides. These elements, referred to as reactive elements in the present invention, increase the already enhanced oxidation and corrosion resistance even further. It has been found that in particular the elements yttrium, hafnium, tantalum, cerium, lanthanum and zirconium are particularly suitable for this purpose.
• the reactive elements can be alloyed both alone and in any combination of the nickel-based alloy.
• the reactive elements are particularly preferably used if their amounts are in a range of less than 1 At. -% lie. Higher quantities are not considered for reasons of cost, moreover, by increased amounts of reactive element also no further improvement of the oxidation and corrosion resistance is achieved.
• Solubility of the two elements in the nickel-based alloy is to lead back. Furthermore, this combination does not lead to the deposition of oxides because of the good solubility.
• a particularly preferred embodiment comprises a spark plug electrode made of an electrode material consisting essentially of nickel as the base material, 0.5 to 2 at. % Silicon and 7 to 10 at. -% aluminum exists.
• an electrode material according to these specifications an extremely balanced ratio of the individual components is present, so that the electrode material not only has maximum oxidation and corrosion resistance and erosion resistance, but also the thermal conductivity is optimized and further the material is simple and inexpensive to produce, without deposits or
• a further preferred embodiment comprises a spark plug electrode made of an electrode material consisting essentially of nickel as a base material, 0.5 to 2
• a combination compared to a corresponding electrode material which contains additive no reactive elements, once again a significant improvement in the oxidation and corrosion resistance.
• the electrode material is thus optimized both in terms of spark erosive wear, thermal conductivity and also the oxidation and corrosion resistance out, resulting in an extremely high life of the electrode material and thus the electrode produced therefrom.
• the erfmdungssiee electrode material for spark plug electrodes can be used both for the Manufacture of the center, as well as the ground electrode as well as both electrodes simultaneously used.
• spark plugs which comprise at least one spark plug electrode according to the invention, and which thus provide improved oxidation and ignition
• Corrosion resistance and have spark erosion resistance and thermal conductivity.

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• 2007
  • 2007-08-29 DE DE102007040722A patent/DE102007040722A1/de not_active Withdrawn
• 2008
  • 2008-07-09 EP EP08774932A patent/EP2186173B1/de not_active Not-in-force
  • 2008-07-09 WO PCT/EP2008/058927 patent/WO2009027139A1/de active Application Filing
  • 2008-07-09 DE DE502008002009T patent/DE502008002009D1/de active Active
  • 2008-07-09 AT AT08774932T patent/ATE491249T1/de active
  • 2008-07-09 JP JP2010522281A patent/JP2010537055A/ja active Pending
  • 2008-07-09 US US12/733,029 patent/US8502438B2/en not_active Expired - Fee Related

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