Corona ignition device with improved electrical performance

A corona igniter for emitting a radio frequency electric field to ionize a fuel-air mixture and provide a corona discharge, comprising:

• a central electrode formed of an electrically conductive material for receiving a high radio frequency voltage and emitting the radio frequency electric field;
• an insulator formed of an electrically insulating material surrounding said central electrode and extending longitudinally along a center axis from an insulator upper end to an insulator nose end;
• said insulator including an insulator outer surface extending from said insulator upper end to said insulator nose end;
• said insulator outer surface presenting an insulator outer diameter extending across and perpendicular to said center axis;
• said insulator including an insulator body region and an insulator nose region;
• said insulator outer surface including a lower ledge extending outwardly away from said center axis between said insulator body region and said insulator nose region;
• said lower ledge presenting an increase in said insulator outer diameter;
• a conductive component surrounding at least a portion of said insulator body region such that said insulator nose region extends outwardly of said conductive component;
• said conductive component including a shell surrounding at least a portion of said insulator body region and extending from a shell upper end to a shell firing end;
• said shell presenting a shell inner surface facing said center axis and extending along said insulator outer surface from said shell upper end to said shell firing end;
• said conductive component including an intermediate part formed of an electrically conductive material and surrounding a portion of said insulator body region and extending longitudinally from an intermediate upper end to an intermediate firing end;
• said intermediate part including an intermediate inner surface facing said center axis and extending longitudinally along said insulator outer surface said from said intermediate upper end to said intermediate firing end;
• said intermediate inner surface presenting a conductive inner diameter extending across and perpendicular to said center axis;
• said conductive inner diameter being less than said insulator outer diameter along a portion of said insulator located between said lower ledge and said insulator nose end;
• said intermediate part being disposed between said insulator upper end and said lower ledge;
• and
• said intermediate part being formed of a metal containing at least one of nickel, cobalt, iron, copper, tin, zinc, silver, and gold;
• or the intermediate part being glass or ceramic based and including at least one of nickel, cobalt, iron, copper, tin, zinc, silver, and gold.