Ignition device having an electrode tip formed from an iridium-based alloy
AssigneesFederal-Mogul Ignition (U.K.) Limited, Johnson Matthey Public Limited Company
InventorsPaul Tinwell, Gurdev Orjela, Robin Hyde, Duncan Roy Coupland
Life of this patent
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Abstract
An ignition device such as a spark plug having ground and center electrodes, at least one of which includes a firing tip formed from an alloy containing iridium, rhodium, tungsten, and zirconium. With the inclusion of tungsten and zirconium in the alloy, the percentage of rhodium can be kept relatively low without sacrificing the erosion resistance or reduced sparking voltage of the firing tip. In one embodiment, the firing tip contains 2% rhodium, 0.3% tungsten, 0.02% zirconium, and the balance iridium.
Claims20
An ignition device for an internal combustion engine, comprising:
- a housing;
- an insulator secured within said housing and having an exposed axial end at an opening in said housing;
- a center electrode mounted in said insulator and extending out of said insulator through said axial end;
- and
- a ground electrode mounted on said housing and terminating at a firing end located opposite said center electrode to define a spark gap therebetween;
- characterized in that at least one of said electrodes includes a firing tip formed from an alloy containing iridium, rhodium, tungsten, and zirconium, wherein said zirconium is present in an amount not greater than 0.05 wt %.
An ignition device for an internal combustion engine, comprising:
- a housing;
- an insulator secured within said housing and having an exposed axial end at an opening in said housing;
- a center electrode mounted in said insulator and extending out of said insulator through said axial end;
- and
- a ground electrode mounted on said housing and terminating at a firing end located opposite said center electrode to define a spark gap therebetween;
- characterized in that at least one of said electrodes includes a firing tip formed from an alloy of metals, wherein the metals consist essentially of iridium, rhodium, tungsten, and zirconium.
An ignition device for an internal combustion engine, comprising:
- a housing;
- an insulator secured within said housing and having an exposed axial end at an opening in said housing;
- a center electrode mounted in said insulator and extending out of said insulator through said axial end;
- and
- a ground electrode mounted on said housing and terminating at a firing end located opposite said center electrode to define a spark gap therebetween;
- characterized in that at least one of said electrodes includes a firing tip formed from an alloy containing iridium, 1-3 wt % rhodium, and zirconium, wherein said zirconium is present in an amount not greater than 0.05 wt %.
Dependencies are inferred from the claim text.