SPARK PLUG AND METHOD FOR MANUFACTURING THE SAME

摘要

Disclosed is a spark plug in which improved weld strength between the distal end of a main fitting and the proximal end of a ground electrode ensures that breakage at the weld portion due to vibration or similar can be avoided even if the diameter of the main fitting is narrowed. Taking the cross sectional area of the weld portion between a main fitting (11) and a ground electrode (14) defined by a plane containing the distal end surface of a main fitting (11) as S2, and the cross-sectional area of the ground electrode (14) defined by a plane that orthogonally intersects the axial direction passing through the leading-most edge in the axial direction of the boundary between the ground electrode (14) and the weld portion as S, a spark plug (100) satisfies the relationship S2?S.