SPARK PLUG FOR INTERNAL COMBUSTION ENGINE

摘要

A spark plug for internal combustion engines is provided to protect a ground electrode against the formation of crystal defects regardless of the flowing direction of an air-fuel mixture. A spark plug(1) for internal combustion engines comprises a cylindrical metal shell(3), a cylindrical isolator(2), a columnar central electrode(5) and a ground electrode(27). The cylindrical metal shell is arranged in an axial direction of the spark plug. The cylindrical isolator is located within the metal shell. The columnar central electrode is arranged within the isolator. The ground electrode whose rear end part is connected to the front end part of the metal shell is extended toward the shaft of the spark plug and bent in order to partition a spark gap between the front end part of the central electrode and the front end part of the ground electrode.