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
  • 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
• • 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

• the present invention relates to a spark plug electrode, on the spark exit or spark entry surface of which an erosion-resistant noble metal is applied.
• Precious metal for example platinum or a platinum alloy
• DE 3 727 526 describes a method for producing a spark plug for internal combustion engines, in which a noble metal plate is connected to the material of the electrode on the end face of the center or ground electrodes by means of laser welding.
• the use of a noble metal particle for welding onto the spark plug electrode which has a smooth surface on the one hand and a profiled surface on the other, has the advantage that the profiled surface has a high contact resistance between the noble metal part and the electrode during the welding process due to the smaller contact area, which means in the welding zone A correspondingly high thermal energy arises between the precious metal part and the spark plug electrode.
• the provision of a smooth surface of the noble metal particle on the side facing the welding electrode in turn has the advantage that here a small one
• the profiling in such a way that the contact surfaces between the noble metal part and the central electrode only exist in the edge region of the noble metal particle at the beginning of the welding process has the advantage that the heating of the Welding precious metal part grows from the edge area towards the center and, due to the star-shaped structure, the air still present between the precious metal part and the electrode can escape via radial channels.
• the welding temperature is relatively uniform over the entire cross-section and can be brought to the desired high values, especially in the critical edge area. This significantly increases the durability of the welded joint, which in turn has a positive effect on the life of the spark plug.
• FIG. 1 shows the spark plug electrode and the noble metal part according to the invention before the welding process
• FIG. 2 shows the top view of the profiled side of the noble metal particle
• FIGS. 3a, 3b, 4a, 4b, 5a and 5b show the individual process steps for producing the profiled noble metal part and its welding on the spark plug electrode.
• Figure 1 shows a cut spark plug electrode 10 and a precious metal part 11 which is placed on the end face of the spark plug electrode 10.
• This precious metal part 11 has a smooth end face 12 and a profiled end face 13.
• the noble metal part 11 is arranged so that it rests with its profiled side 13 on the spark plug electrode 10.
• the welding electrode 14 is shown schematically on the side facing away from the spark plug electrode 10 with a smooth surface 12 of the noble metal 11.
• Figure 2 should be used.
• FIG. 2 components that have already been explained for FIG. 1 are provided with the same reference symbols.
• Profiling of the noble metal particle 11 is designed such that the contact surface 20 is located on the outer edge of the noble metal particle 11 between the spark plug electrode 10 and the noble metal part 11. As can be seen in FIG. 2, a star-shaped profile was selected here, which ensures that only the outer regions initially form a contact surface 20 with the spark plug electrode 10.
• FIGS. 3a and 3b The manufacture of the profiled precious metal part according to the invention and its welding to the central electrode will now be explained with reference to FIGS. 3a and 3b, FIGS. 4a and 4b and FIGS. 5a and 5b. Since all the figures relate to the same object, the same reference numerals are used for the same components, which are then not explained again completely anew for the respective figures.
• a noble metal wire 30, for example a platinum wire is guided through a holding part 31 such that the noble metal wire 30 protrudes from this holder 31 in a controlled manner on the other side.
• the length of the precious metal part can be determined by setting or preselecting the protrusion of the precious metal part.
• the portion of the noble metal wire 30 which projects out of the holding part 31 is now sheared off by means of a shearing tool 32.
• one noble metal cutling 40 has already been sheared off the noble metal wire 30. With this inspection method, a relatively large length of the precious metal collar 40 can be achieved even with a relatively small wire diameter.
• the ratio of The length to diameter of the precious metal hemisphere is advantageously greater than 1.
• the precious metal cutling 40 is arranged in a stamping tool (not explained in more detail) between two stamping dies 41 and 42 and is compressed in order to increase the diameter or reduce the length.
• a first stamp 41 with a smooth surface and a second stamp 42 with a profiled surface are provided. Due to this arrangement, the noble metal cutling 40 is embossed into the shape already explained in relation to FIG. 1 during the setting process shown in FIG. one surface has a smooth or planar shape and the opposite surface of the noble metal part 11 has a profiled surface.
• the noble metal part 11 shaped in this way is now, as shown in FIG. 5a, placed on the spark plug electrode 10, for example a central electrode in such a way that the side with the smooth surface 12 is opposite the welding electrode 14.
• This provides a good contact surface with a low contact resistance between the noble metal part 11 to be welded and the welding electrode 14.
• the profiled end face 13 of the noble metal part 11 is arranged opposite the spark plug electrode, so that there is a high contact resistance which is advantageous for the welding process between the spark plug electrode and the noble metal part 11.
• the welding process itself is preferably carried out in two stages, with the profile tips on the contact surfaces 20 being welded with a relatively low current in a first stage. This creates uniform starting conditions for the second welding stage. In the second welding stage, the precious metal is coated with a higher current strength until the full-surface connection to the electrode is welded.
• FIG. 5b shows the connection between spark plug electrode 10 and precious metal part 11 after the welding process.
• This welded composite can now be fed to further processing stages. For example, when used as a center electrode, it is conceivable to chamfer this composite in its edge region in order to ensure that the noble metal particle reaches the furthest to the opposite electrode of the spark plug.
• the described method enables a largely free design of the precious metal part on the spark plug electrode.

Landscapes

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

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=7878618

Family Applications (1)

Country Status (5)

Cited By (2)

Families Citing this family (8)

Citations (2)

Family Cites Families (2)

• 1998
  • 1998-08-25 DE DE19838538A patent/DE19838538A1/de not_active Withdrawn
• 1999
  • 1999-04-09 US US09/763,510 patent/US6630771B1/en not_active Expired - Fee Related
  • 1999-04-09 WO PCT/DE1999/001072 patent/WO2000013274A1/de not_active Ceased
  • 1999-04-09 JP JP2000568154A patent/JP2002524821A/ja active Pending
  • 1999-04-09 EP EP99968269A patent/EP1110284B1/de not_active Expired - Lifetime
  • 1999-04-09 DE DE59909919T patent/DE59909919D1/de not_active Expired - Lifetime

Patent Citations (2)

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