SPARK PLUG

摘要

A spark plug includes an insulator having an axial hole, a center electrode inserted into a forward portion of the axial hole, a terminal electrode inserted into a rear portion of the axial hole, and an interelectrode insert which contains glass and electrically conductive carbon and is disposed in the axial hole between the center electrode and the terminal electrode. The interelectrode insert has a resistance of 1.0 kΩ to 3.0 kΩ, and the interelectrode insert has a carbon content of 1.5% by mass to 4.0% by mass at a forward portion located forward of a center point between the rear end of the center electrode and the forward end of the terminal electrode. Furthermore, the forward portion is lower in resistance than a rear portion of the interelectrode insert located rearward of the center point.

主权项

1. A spark plug comprising:
an insulator having an axial hole extending therethrough along an axial line; a center electrode inserted into a forward end side of the axial hole; a terminal electrode inserted into a rear end side of the axial hole; and an interelectrode insert which contains glass and electrically conductive carbon and is disposed in the axial hole between the center electrode and the terminal electrode; the spark plug being characterized in that the interelectrode insert has a carbon content of 1.5% by mass to 4.0% by mass at a forward portion located forward of a center point along the axial line between a rear end of the center electrode and a forward end of the terminal electrode; the interelectrode insert has a resistance of 1.0 kΩ to 3.0 kΩ; and the forward portion is lower in resistance than a rear portion of the interelectrode insert located rearward of the center point along the axial line between the rear end of the center electrode and the forward end of the terminal electrode.