IGNITION PLUG

摘要

A spark plug has a metal shell and a cylindrical ceramic insulator disposed in an inner circumference of the metal shell. An axial hole extends in an axial line CL direction through the insulator, and has a tip located more to a tip side of the spark plug than a tip of the metal shell, and a distance along the axial line CL1 from the tip of the metal shell to the tip of the ceramic insulator is 0.5 mm or more. The insulator satisfies C≧1.07 mm and V≦3.9 mm3, where C is a thickness of the insulator in a cross section passing an inner circumference surface tip of the metal shell and orthogonal to the axial line CL1, and V is a volume of the ceramic insulator within a range of 0.5 mm from the tip of the ceramic insulator to a rear end side in the axial line CL1 direction.

主权项

1. A spark plug comprising:
a cylindrical metal shell; and a cylindrical insulator disposed in an inner circumference of the metal shell, having an axial hole extending in an axial direction, and having a tip located more to a tip side of the spark plug than a tip of the metal shell, wherein a distance along the axial line from the tip of the metal shell to the tip of the insulator is 0.5 mm or more, and wherein C≧1.07 mm and V≦3.9 mm3 are satisfied, where C is a thickness of the insulator in a cross section that passes a tip of an inner circumference surface of the metal shell and that is orthogonal to the axial line, and V is a volume of the insulator within a range of 0.5 mm from the tip of the insulator to a rear end side in the axial direction.