MULTIPOLAR SPARK PLUG AND SEMI-CREEPING MULTIPOLAR SPARK PLUG

摘要

PROBLEM TO BE SOLVED: To provide a multipole spark plug and a semi-creeping multipolar spark plug having a long service life, regardless of the directionality of an outside electrode after it is assembled, and having superior ignitability.;SOLUTION: This multipole spark plug is equipped with a main metal fitting 1, an insulator 2 fitted to the main metal fitting 1, while having a spindle hole, a center electrode 3 fitted into the spindle hole, and two outside electrodes 4a, 4b welded to the tip surface of the main metal fitting 1, while having the facing surfaces 41a, 41b of the outside electrodes, so as to face the peripheral surface of the center electrode 3. Among gap distances (G) in between the facing surfaces 41a, 41b of the outside electrodes and the peripheral surface 31 of the center electrode 3 facing the facing surfaces 41a, 41b of the outside electrodes, the difference between the maximum distance and the minimum distance is not more than 0.30 mm. In addition, the gap distance between the electrodes is not more than 0.9 mm.;COPYRIGHT: (C)2003,JPO