SPARK PLUG Russian patent published in 2000 - IPC

FIELD: electrical engineering; internal-combustion engines. SUBSTANCE: spark plug has shell, central electrode placed in insulator, and at least one ground electrode spaced through air gap from insulator and through spark gap, from central electrode. With spark gap chosen between 1.7 and 4.9 mm air gap is between 0.4 and 0.8 mm at lower end of spark gap and between 0.4 and 0.6 mm at its upper end. Central electrode juts beyond adjacent insulator edge through distance not over one third of its diameter. Spark-receiving surface edge facing spark-plug interior is located within insulator butt-end surface and its displacement in same direction is not to exceed 0.2 mm. Butt-end surface of insulator may be made flat in the form of circular ring or in the form of part of cylinder or cone with coverage angle of minimum 30 deg. Ground electrode may be made in the form of segmental strap placed on shell and provided with insulating insert. EFFECT: enlarged length of spark discharge, increased service life of plug, and reduced probability of its overheating. 11 cl, 5 dwg