Spark plug with ground electrode inserted into the housing wall and with improved heat balance

A spark plug with a longitudinal axis, comprising:

• a housing with a longitudinal bore parallel to the longitudinal axis of the spark plug, the housing having a housing wall and an interior;
• an insulator arranged within the housing;
• a center electrode arranged within the insulator;
• a ground electrode with a total length LMaEl and a diameter DMaEl,
• a bore in the housing wall with a diameter DBohr, wherein the ground electrode is arranged with a length LBohr in the bore, and the ground electrode projects with a length Lem from an inner side of the housing wall into the interior of the housing, and wherein the housing wall has a thickness LWall in a region of the bore;
• and
• a spark gap formed between the ground electrode and the center electrode;
• wherein:
• (i) a ratio of the total length LMaEl of the ground electrode to the length LBohr of the ground electrode in the bore is equal to or greater than 1.8 and equal to or less than 2.2, and/or (ii) the ratio of the length Lem, with which the ground electrode projects into the interior of the housing, to the thickness LWall of the housing wall is equal to or greater than 0.2 and is equal to or less than 3, wherein the total length LMaEl of the ground electrode, the length LBohr of the ground electrode in the bore, the length Lem with which the ground electrode projects into the interior of the housing, and the thickness LWall of the housing wall, extend perpendicularly to the longitudinal axis of the spark plug.