Spark plug having a small inter-electrode distance and an at least partly negative spark position

A spark plug having a longitudinal axis, comprising:

• a housing having a bore along the spark plug longitudinal axis and a combustion-chamber-side end face;
• an insulator arranged at least partially within the housing, the insulator having an insulator base which extends from a combustion-chamber-side end face of the insulator to an insulator base neck;
• a central electrode arranged at least partially within the insulator;
• and
• at least one ground electrode arranged on the housing, the at least one ground electrode and the central electrode being arranged in such a way that the at least one ground electrode forms a spark gap with the central electrode, a width of the spark gap being defined by an inter-electrode distance between the central electrode and the at least one ground electrode,
• wherein the inter-electrode distance between the central electrode and the at least one ground electrode is not greater than 0.4 mm, and the spark gap is formed at least partially within the housing, and
• wherein the insulator base has a length, measured parallel to the longitudinal axis of the spark plug, which is not longer than 7 mm.

A spark plug having a longitudinal axis, comprising:

• a housing having a bore along the spark plug longitudinal axis and a combustion-chamber-side end face;
• an insulator arranged at least partially within the housing, the insulator having an insulator base which extends from a combustion-chamber-side end face of the insulator to an insulator base neck;
• a central electrode arranged at least partially within the insulator;
• and
• at least one ground electrode arranged on the housing, the at least one ground electrode and the central electrode being arranged in such a way that the at least one ground electrode forms a spark gap with the central electrode, a width of the spark gap being defined by an inter-electrode distance between the central electrode and the at least one ground electrode,
• wherein the inter-electrode distance between the central electrode and the at least one ground electrode is not greater than 0.4 mm, and the spark gap is formed at least partially within the housing, and
• wherein the central electrode protrudes from the insulator, and a protrusion dimension of the central electrode, measured from the combustion-chamber-side end face of the insulator as far as a combustion-chamber-side end of the central electrode, is not greater than 6.0 mm and is not smaller than 0.5 mm.

A spark plug having a longitudinal axis, comprising:

• a housing having a bore along the spark plug longitudinal axis and a combustion-chamber-side end face;
• an insulator arranged at least partially within the housing, the insulator having an insulator base which extends from a combustion-chamber-side end face of the insulator to an insulator base neck;
• a central electrode arranged at least partially within the insulator;
• and
• at least one ground electrode arranged on the housing, the at least one ground electrode and the central electrode being arranged in such a way that the at least one ground electrode forms a spark gap with the central electrode, a width of the spark gap being defined by an inter-electrode distance between the central electrode and the at least one ground electrode,
• wherein the inter-electrode distance between the central electrode and the at least one ground electrode is not greater than 0.4 mm, and the spark gap is formed at least partially within the housing, and
• wherein the spark plug has a breathing chamber which extends within the housing from the combustion-chamber-side end face of the housing to the insulator base neck, the central electrode and the insulator base being arranged within the breathing chamber and the at least one ground electrode being arranged at least partially within the breathing chamber, and the breathing chamber has a volume of not greater than 500 mm3 and not less than 50 mm3.