Patent attributes
A spark plug having a protrusion amount t of not smaller than 0.3 mm and satisfying a relation θ1+θ2≦93° in which θ1 is an included angle between virtual lines s1 and s2, and θ2 is an included angle between virtual lines s3 and s4 when the virtual line s1 is taken as a line parallel to a direction of an axis and including the other end side edge on a leading end surface of a first precious metal tip, the virtual line s2 is taken as a line connecting the other end side edge and a point of intersection between an inner circumferential surface of a ground electrode body and the other end surface of the ground electrode body, the virtual line s3 is taken as a line parallel to the direction of the axis and including the other end side edge on a leading end surface of a center electrode, and the virtual line s4 is taken as a line including the other end side edge and tangent to an insulator.
