Patent ID: 6853116
Filing Date: 2005-02-08
Classification: H01T

Abstract:
1. A spark plug comprising: a center electrode having a tip; a ground electrode having a center electrode-opposed surface facing the tip of said center electrode; a noble metal member having a given length and a first and a second end opposed to each other through the length, said noble metal member being joined at the first end to the center electrode-opposed surface of said ground electrode by laser welding so as to oppose the second end to the tip of said center electrode through a spark gap; and a fused portion that forms a weld of said noble metal member and said ground electrode formed by materials of said ground electrode and said noble metal member melted together, wherein a sectional area of said noble metal member traversing the length thereof is greater than or equal to 0.1 mm wherein an unfused sectional area percentage that is a percentage of a sectional area of an unfused portion of the first end of said noble metal member within a range of a sectional area of said noble metal member closest to said fused portion traversing the length of said noble metal member is less than or equal to 50%, and wherein a melt angle that is an angle which a line extending through said fused portion along a maximum depth of said fused portion makes with the center electrode-opposed surface of said ground electrode is less than or equal to 60°.