SPARK PLUG AND MANUFACTURING METHOD THEREOF

• Main Authors: KIUMI TAKAAKI, KUNO TAKEHITO, SHIBATA TSUTOMU, YOSHIMOTO OSAMU
• Format: Patent
• Language: English
• Published: 27.06.2013
• Subjects: BASIC ELECTRIC ELEMENTS; CORONA DEVICES; ELECTRICITY; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARK GAPS; SPARKING PLUGS

PROBLEM TO BE SOLVED: To realize superior deformation resistance of a ground electrode while achieving improvement of wear resistance of the ground electrode.SOLUTION: A spark plug 1 comprises: a center electrode 5; and a ground electrode 27, with a spark discharge gap 33 being formed between the center electrode 5 and the ground electrode 27. The ground electrode 27 comprises: an outer cover part 28 made of a metal containing 93% by mass or more of Ni; and a heat radiation part 29 provided inside the outer cover part 28 and having thermal conductivity that is higher than that of the outer cover part 28. When a protrusion amount of the ground electrode 27 from a tip end of a main metal fitting 3 along an axis line CL1 is referred to as L (mm), in a cross section that passes through an intersection CP between a plane, which exists at a position displaced from the tip end of the main metal fitting 3 along the axis line CL1 by L/2 on a tip end side in an axis line CL1 direction and is orthogonal to the axis line CL1, and a center axis CL2 of the ground electrode 27 and is orthogonal to the center axis CL2, a cross sectional area of the outer cover part 28 is set equal to or less than 80% of that of the ground electrode 27. Also, hardness of the outer cover part 28 is set in a range between 110Hv and 220Hv inclusive in terms of Vickers hardness.