| 摘要 |
A spark plug which satisfies phiB<=0.8 mm, phiB/phiA>=1.4, and 0.5 mm<=C<=1.2 mm, where phiA (mm) is the diameter of a distal end portion ( 51 ) formed of a noble metal tip ( 51 b) of a center electrode 3 ; phiB (mm) is the diameter of a discharge portion ( 52 ) formed of a noble metal tip ( 52 b) of a ground electrode ( 4 ); and C (mm) is a projection length of the discharge portion ( 52 ) from an electrode base metal surface ( 4 a).
|
