| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a technique capable of improving a welding strength of a ground electrode and a noble metal chip. <P>SOLUTION: A molten part formed by melting a ground electrode and a noble metal chip is provided on at least one part between the ground electrode and the noble metal chip of a spark plug. On a first section passing through a center of gravity of the noble metal chip and cut by a plane vertical to a width direction of the ground electrode, when thickness of a thickest portion of the molten part is designated as A and length of a longest portion of the molten part is designated as B, a relationship of 1.5≤B/A is satisfied. On a second section vertical to the discharge surface of the noble metal chip, passing through the center of gravity of the noble metal chip, and cut by a plane parallel to the width direction of the ground electrode, when length of the discharge surface of the noble metal chip is designated as C and length of the molten part in a direction parallel to the discharge surface is designated as D, a relationship of 1.2≤D/C is satisfied. <P>COPYRIGHT: (C)2012,JPO&INPIT |
