Patent attributes
A spark plug having a multilayer firing tip that minimizes the amount of precious metal used and a method of assembling a spark plug with a multilayer firing tip. The firing tip includes a discharge end and a weld end, with the weld end being connected to a center electrode, and more specifically to a base electrode on the center electrode. The weld end has a coefficient of thermal expansion, which is not between the values for the coefficients of thermal expansion for the discharge end and the base electrode. More specifically, the weld end has a coefficient of thermal expansion which is greater than the coefficients of thermal expansion for the discharge end and base electrode. The weld end is formed from Nickel and Chromium with a limited amount of additional elements. The spark plug is assembled by providing a first elongated material formed from the material used for the discharge end and a second elongated material formed from a material used for the weld end. The two materials are then joined to form a single joined material and are severed to create a firing tip. The firing tip is welded to the center electrode of the spark plug and more specifically, the base electrode.
