Patent ID: 7288879
Filing Date: 2007-10-30
Classification: H01T

Abstract:
1. A spark plug comprising: a cylindrical metal shell; a cylindrical insulator fixed in said metal shell; a center electrode having its leading end protruding from a leading end of said insulator and its trailing end fixed to said insulator; and a ground electrode having one end fixed to said metal shell and forming a discharge gap between said ground electrode and said center electrode, wherein said ground electrode includes a precious metal alloy portion containing: 50 weight % or more of a first component of one of Rh and Pt; less than 50 weight % of a second component of the other of Rh and Pt; and a third component including Zr in an amount of 0.5 weight % to less than 2 weight % and optionally Ni in an amount of 0.5 weight % to less than 7 weight %, the total content of said third component being less than that of said second component.