| 摘要 |
PROBLEM TO BE SOLVED: To provide a spark plug enhancing durability of an ignition part of a ground electrode. SOLUTION: A spark plug 100 comprises a central electrode 3; an insulator 2 disposed outside the central electrode 3; a main body fitting 1 disposed outside the insulator 2; a ground electrode 4 arranged so as to face the central electrode 3; and ignition parts 31, 32 welded to the central electrode 3 and the ground electrode 4 to form a spark discharge gap g. The ignition part 32 of the ground electrode 4 is made of a precious-metal alloy consisting of a main component element and an additional element component and forms a welded part W by laser welding to joint to the ground electrode 4. A distance from the tip surface 32s of the ignition part 32 of the ground electrode 4 to the tip edge of the welded part W is≥0.2 mm, a stripe-like density irregularity is generated in a density distribution of the additional element component in the precious-metal alloy and a direction of the density irregularity stripe is so arranged to be nearly perpendicular to a voltage applying direction at the ignition part 32. COPYRIGHT: (C)2006,JPO&NCIPI
|
