| 主权项 |
1. A spark plug for being threaded into a cylinder head and extending into a combustion chamber for providing a spark to ignite a combustible mixture of fuel and air in the combustion chamber, comprising:
a central electrode formed of an electrically conductive material extending longitudinally along an igniter central axis from an electrode terminal end to an central firing end, said electrically conductive material of said central electrode being a nickel-based material including nickel in an amount of at least 60.0 wt. %, based on the total weight of said nickel-based material, said central electrode including a central firing tip formed of a precious metal alloy and disposed on said central firing end for providing the spark, an insulator formed of an electrically insulating material surrounding said central electrode and extending longitudinally along said igniter central axis to an insulator nose end such that said central firing end is disposed outwardly of said insulator nose end, said insulator including an insulator bore extending along said igniter central axis for receiving said central electrode, said electrically insulating material including alumina, a terminal formed of an electrically conductive material received in said insulator and extending longitudinally along said igniter central axis to a second terminal end electrically connected to said electrode terminal end, a resistor layer disposed between and electrically connecting said second terminal end and said electrode terminal end for transmitting energy from said terminal to said central electrode, said resistor layer being formed of an electrically resistive material, said electrically resistive material being a glass seal, a shell formed of metal material surrounding said insulator and extending longitudinally along said igniter central axis from a shell upper surface to a shell lower surface such that said insulator nose end extends outwardly of said shell lower surface, said metal material including steel, said shell lower surface being planar and perpendicular to said igniter central axis and extending annularly around said insulator, said shell lower surface presenting a shell thickness, said shell including a shell inner surface facing said insulator and a shell outer surface facing opposite said shell inner surface each extending circumferentially around said igniter center axis and longitudinally between said shell upper surface and said shell lower surface, said shell inner surface presenting a shell inner diameter and said shell outer surface presenting a shell outer diameter each extending across said igniter central axis, a ground electrode formed of the electrically conductive material extending and curving from an attachment surface disposed on said shell lower surface to a ground firing surface spaced from said central firing end, said ground electrode including a side surface extending between said attachment surface and said ground firing surface, said attachment surface and said ground firing surface being planar and presenting an electrode thickness not greater than said shell thickness, said attachment surface of said ground electrode being planar and welded to said shell lower surface, said attachment surface of said ground electrode being disposed at a predetermined circumferential location along said shell lower surface, said electrically conductive material of said ground electrode being a nickel-based material including nickel in an amount of at least 60.0 wt. %, based on the total weight of said nickel-based material, said ground electrode including a ground firing tip formed of a precious metal alloy disposed on said ground firing surface for providing said spark, said ground firing tip being spaced from said central firing tip to provide a spark gap therebetween, said shell outer surface presenting a plurality of threads extending circumferentially around said igniter central axis between said shell upper surface and said shell lower surface for engaging mating threads of the cylinder head, each of said threads presenting a thread diameter across said igniter central axis (ai) of 10 to 18 mm, each of said threads being spaced from an adjacent thread, said threads being disposed at a predetermined angle relative to said side surface of said ground electrode adjacent said attachment surface allowing said ground electrode to be disposed in a predetermined position in the combustion chamber when said shell is threaded into the cylinder head, and said threads being disposed at an angle (α) of plus or minus a certain degree from a plane perpendicular to said igniter central axis (ai) and extending through a predetermined point (P) along said shell outer surface. |
