Spark plug
AssigneeFederal-Mogul Ignition Company
InventorShuwei Ma
Life of this patent
Estimating the term…
Abstract
A spark plug having a firing pad with minimal silicon diffusion and limited silicon oxidation at grain boundaries that can cause undesirable vertical cracking. In one embodiment, the firing pad has a multilayer structure having a base layer and a firing layer, wherein the base layer is a non-precious metal based material having silicon, and wherein the firing layer is a precious metal based material having yttrium in an amount of 0.1 to 0.5 wt %, inclusive. After at least 190 hours of isothermal treatment of at least 1000° C., an extent of vertical cracking from the sparking surface does not exceed 50% of a thickness of the firing pad or the firing layer.
Claims20
A spark plug, comprising:
- a shell having an axial bore;
- an insulator disposed at least partially within the axial bore of the shell;
- a center electrode disposed at least partially within the axial bore of the insulator;
- a ground electrode configured to create a spark gap with the center electrode;
- and
- a firing pad attached to the center electrode or the ground electrode, wherein the firing pad has a multilayer structure having a base layer and a firing layer, wherein the base layer is a non-precious metal based material having silicon, and wherein the firing layer is a precious metal based material having yttrium in an amount of 0.1 to 0.5 wt %, inclusive, and wherein the non-precious metal based material of the base layer has 50 wt % or more of non-precious metal, wherein the base layer is a backing for the firing layer to create a weldment that is at least partially separate from the non-precious metal material of the base layer.
A spark plug, comprising:
- a shell having an axial bore;
- an insulator disposed at least partially within the axial bore of the shell;
- a center electrode disposed at least partially within the axial bore of the insulator;
- a ground electrode configured to create a spark gap with the center electrode;
- and
- a firing pad attached to the center electrode or the ground electrode, wherein the firing pad has a sparking surface, wherein the firing pad is a precious metal based material, the precious metal based material having 50 wt % or more of platinum (Pt) and/or iridium (Ir), the precious metal based material having a rare earth element selected from the group of yttrium (Y), hafnium (Hf), scandium (Sc), lanthanum (La), cerium (Ce), and zirconium (Zr) in an amount of 0.1 to 1.0 wt %, inclusive, and wherein after at least 190 hours of isothermal treatment of at least 1000° ° C., an extent of vertical cracking does not exceed 50% of a thickness of the firing pad.
A spark plug, comprising:
- a shell having an axial bore;
- an insulator disposed at least partially within the axial bore of the shell;
- a center electrode disposed at least partially within the axial bore of the insulator;
- a ground electrode configured to create a spark gap with the center electrode;
- and
- a firing pad attached to the center electrode or the ground electrode, wherein the firing pad has a sparking surface and a multilayer structure having a base layer and a firing layer, wherein the base layer is a non-precious metal based material having silicon, and wherein the firing layer is a precious metal based material having yttrium in an amount of 0.1 to 0.5 wt %, inclusive, wherein the non-precious metal based material of the base layer has 50 wt % or more of non-precious metal, and wherein the firing pad has a voiding layer extending substantially horizontal at least partially between the base layer and the sparking surface.
Dependencies are inferred from the claim text.