SPARK PLUG FOR INTERNAL COMBUSTION ENGINE, AND ATTACHMENT STRUCTURE FOR SPARK PLUG

WIPO Patent Application WO/2013/065743

A1

Provided is a spark plug (1) equipped with a housing (2), an insulator (3), a center electrode (4), a main ground electrode (51), a first sub ground electrode (52), and a second sub ground electrode (53). The first sub ground electrode (52) and the second sub ground electrode (53) are disposed facing one another. When Hc represents the protrusion length of the center electrode (4), Gm represents the size of a main gap (61), Hs1 represents the protrusion length of the first sub ground electrode (52), Hs2 represents the protrusion length of the second sub ground electrode (53), Gs1 represents the plug radial direction length of a first sub gap (62), Gs2 represents the plug radial direction length of a second sub gap (63), and Gg represents the plug radial direction distance between the outer circumference angle part (311) and the inner circumference angle part (312) of an insulator tip (31), the following conditions are satisfied: Hs1