Patent ID: 7663296

Claim:
A spark plug having a leading side and a base side, said spark plug comprising: a cylindrical insulator having an axial hole extending through the insulator in an axial direction; a center electrode inserted in the axial hole; a metal shell provided around an outer periphery of the insulator and having a leading end surface, from which a leading end surface of the insulator protrudes; one or more ground electrodes having a base end bonded to the leading end surface of the metal shell; and a noble metal tip having a first end disposed on a distal tip end surface of the one or more ground electrodes, a second end of the noble metal tip protruding toward the center electrode in a radial direction, and the second end of the noble metal tip facing at least a part of the end of the insulator, wherein: said spark plug forming a spark discharge path upon application of a discharging voltage between the second end of the noble metal tip and an end of the center electrode, said spark discharge path comprising an aerial discharge gap between a part of the second end of the noble metal tip and a part of the end of the insulator and a surface-creeping discharge path beginning at a part of the end of the insulator and a part of the center electrode and extending along the end surface of the insulator; and said noble metal tip protruding from the distal end of the ground electrode by a protruding length of more than 0.2 mm.