Abstract: A prechamber spark plug that includes an internal reservoir, a flow passage portion, and a prechamber and is designed to operate efficiently across a wide variety of operating conditions and ranges. The internal reservoir includes upper and lower internal reservoir sections, the prechamber includes upper and lower prechamber sections, and the flow passage portion fluidly connects the lower internal reservoir section and the upper prechamber section so that burnt air/fuel gases can be exchanged therebetween. A ground electrode assembly with a ground electrode ring may be positioned in the prechamber such that it separates the upper and lower prechamber sections, whereas a modular prechamber cap may be used to define the shape and size of the lower prechamber section. In one example, the flow passage portion has a total cross-sectional area (AFC) and the internal reservoir has a total volume (VRES), and the ratio AFC:VRES is greater than or equal to 0.015 (1/mm).

Abstract: A corona comprises a central electrode surrounded by an insulator, which is surrounded by a conductive component. The conductive component includes a shell and an intermediate part both formed of an electrically conductive material. The intermediate part is a layer of metal which brazes the insulator to the shell. An outer surface of the insulator presents a lower ledge, and the layer of metal can be applied to the insulator above the lower ledge prior to or after inserting the insulator into the shell. The conductive inner diameter is less than an insulator outer diameter directly below the lower ledge such the insulator thickness increases toward the electrode firing end. The insulator outer diameter is also typically less than the shell inner diameter so that the corona igniter can be forward-assembled.

Abstract: A pre-chamber spark plug includes a shell extending along a longitudinal axis and comprising an inner surface. The pre-chamber spark plug further includes an insulator including an outer surface. The pre-chamber spark plug further includes a pre-chamber cap connected to the shell. The pre-chamber cap and the shell together forms a pre-chamber. The pre-chamber spark plug further includes an annular reservoir defined between the outer surface of the insulator and the inner surface of the shell. The annular reservoir is spaced apart from the pre-chamber with respect to the longitudinal axis. The pre-chamber spark plug further includes a plurality of projections disposed between the annular reservoir and the pre-chamber with respect to the longitudinal axis. The plurality of projections at least partially define a plurality of flow passages therebetween.

Abstract: A corona comprises a central electrode surrounded by an insulator, which is surrounded by a conductive component. The conductive component includes a shell and an intermediate part both formed of an electrically conductive material. The intermediate part is a layer of metal which brazes the insulator to the shell. An outer surface of the insulator presents a lower ledge, and the layer of metal can be applied to the insulator above the lower ledge prior to or after inserting the insulator into the shell. The conductive inner diameter is less than an insulator outer diameter directly below the lower ledge such the insulator thickness increases toward the electrode firing end. The insulator outer diameter is also typically less than the shell inner diameter so that the corona igniter can be forward-assembled.

Abstract: A corona comprises a central electrode surrounded by an insulator, which is surrounded by a conductive component. The conductive component includes a shell and an intermediate part both formed of an electrically conductive material. The intermediate part is a layer of metal which brazes the insulator to the shell. An outer surface of the insulator presents a lower ledge, and the layer of metal can be applied to the insulator above the lower ledge prior to or after inserting the insulator into the shell. The conductive inner diameter is less than an insulator outer diameter directly below the lower ledge such the insulator thickness increases toward the electrode firing end. The insulator outer diameter is also typically less than the shell inner diameter so that the corona igniter can be forward-assembled.

Abstract: An insulator for a corona igniter, referred to as a barrier discharge ignition (BDI) device, for use in an internal combustion engine, is provided. A central electrode is disposed in a slot of the insulator and an electrode tip is spaced from a round insulator tip by insulating material. A shell formed of metal surrounds a portion of the insulator. The insulator has a thickness tapering between a shell firing surface and the insulator tip. The tapering insulator thickness is unidirectional and thus does not increase between a start of the taper and the insulator tip. A method of manufacturing an insulator for a corona igniter is also provided. Equations can be used to determine if a taper in the insulator thickness is needed to encourage corona propagation along a core nose projection of the insulator, and if so, the location and size of the taper.

Abstract: An igniter assembly comprising an ignition coil assembly connected to a firing end assembly by an extension, with a valve assembly disposed in a pressure chamber of the extension, is provided. The valve assembly includes a valve stem biased toward the ignition coil assembly by a spring to seal the pressure chamber. The valve assembly is used to evacuate contents from the pressure chamber by pressing the valve stem toward the spring and allowing contents of the pressure chamber to travel through and past the valve stem and out of the pressure chamber. The valve assembly is also used to fill the pressure chamber with an insulating medium by pressing the valve stem toward the spring and allowing the insulating medium to travel through and past the valve stem and into the pressure chamber after evacuating the contents out of the pressure chamber.

Abstract: A firing tip for a corona igniter is provided. The firing tip includes a base formed of metal, such as nickel, and rivets formed of precious metal, such as iridium. The base includes indentations, and the rivets are disposed in the indentations of the base. The rivet has a melting point and/or wear resistance greater than the base. Typically, the indentations of the base include a concave surface and the rivets have a cylindrical shape matching the shape of the indentations. The rivets can be sharpened to a point. The rivets can include a first piece formed of precious metal and a second piece formed of nickel or nickel alloy, wherein an end of the first piece is welded to an end of the second piece, and the second piece is welded to the base. Alternatively, the rivets can be formed entirely of the precious metal.

Abstract: An insulator for a corona igniter, referred to as a barrier discharge ignition (BDI) device, for use in an internal combustion engine, is provided. A central electrode is disposed in a slot of the insulator and an electrode tip is spaced from a round insulator tip by insulating material. A shell formed of metal surrounds a portion of the insulator. The insulator has a thickness tapering between a shell firing surface and the insulator tip. The tapering insulator thickness is unidirectional and thus does not increase between a start of the taper and the insulator tip. A method of manufacturing an insulator for a corona igniter is also provided. Equations can be used to determine if a taper in the insulator thickness is needed to encourage corona propagation along a core nose projection of the insulator, and if so, the location and size of the taper.

Abstract: An igniter, such as a corona igniter for an internal combustion engine, and a method of manufacturing the igniter, are provided. The igniter includes an insulator with enlarged upper and lower end regions extending axially beyond opposite ends of a constrained, reduced diameter region of a shell through passage. The enlarged lower end region of the insulator is disposed axially outwardly of a lower end of the shell. The insulator is hermetically sealed to the shell and is permanently fixed against being removed axially outwardly from the shell. The method can include conforming the shell to the contour of the insulator by plastically deforming the shell, or casting the shell about the insulator. Alternatively, separate pieces of metal can be disposed around the insulator to form the shell which is conformed to the insulator.

Abstract: A corona comprises a central electrode surrounded by an insulator, which is surrounded by a conductive component. The conductive component includes a shell and an intermediate part both formed of an electrically conductive material. The intermediate part is a layer of metal which brazes the insulator to the shell. An outer surface of the insulator presents a lower ledge, and the layer of metal can be applied to the insulator above the lower ledge prior to or after inserting the insulator into the shell. The conductive inner diameter is less than an insulator outer diameter directly below the lower ledge such the insulator thickness increases toward the electrode firing end. The insulator outer diameter is also typically less than the shell inner diameter so that the corona igniter can be forward-assembled.

Abstract: A corona comprises a central electrode surrounded by an insulator, which is surrounded by a conductive component. The conductive component includes a shell and an intermediate part both formed of an electrically conductive material. The intermediate part is a layer of metal which brazes the insulator to the shell. An outer surface of the insulator presents a lower ledge, and the layer of metal can be applied to the insulator above the lower ledge prior to or after inserting the insulator into the shell. The conductive inner diameter is less than an insulator outer diameter directly below the lower ledge such the insulator thickness increases toward the electrode firing end. The insulator outer diameter is also typically less than the shell inner diameter so that the corona igniter can be forward-assembled.

Abstract: An igniter assembly comprising an ignition coil assembly connected to a firing end assembly by an extension, with a valve assembly disposed in a pressure chamber of the extension, is provided. The valve assembly includes a valve stem biased toward the ignition coil assembly by a spring to seal the pressure chamber. The valve assembly is used to evacuate contents from the pressure chamber by pressing the valve stem toward the spring and allowing contents of the pressure chamber to travel through and past the valve stem and out of the pressure chamber. The valve assembly is also used to fill the pressure chamber with an insulating medium by pressing the valve stem toward the spring and allowing the insulating medium to travel through and past the valve stem and into the pressure chamber after evacuating the contents out of the pressure chamber.

Abstract: An igniter assembly comprising an ignition coil assembly connected to a firing end assembly by an extension, with a valve assembly disposed in a pressure chamber of the extension, is provided. The valve assembly includes a valve stem biased toward the ignition coil assembly by a spring to seal the pressure chamber. The valve assembly is used to evacuate contents from the pressure chamber by pressing the valve stem toward the spring and allowing contents of the pressure chamber to travel through and past the valve stem and out of the pressure chamber. The valve assembly is also used to fill the pressure chamber with an insulating medium by pressing the valve stem toward the spring and allowing the insulating medium to travel through and past the valve stem and into the pressure chamber after evacuating the contents out of the pressure chamber.

Abstract: A firing tip for a corona igniter is provided. The firing tip includes a base formed of metal, such as nickel, and rivets formed of precious metal, such as iridium. The base includes indentations, and the rivets are disposed in the indentations of the base. The rivet has a melting point and/or wear resistance greater than the base. Typically, the indentations of the base include a concave surface and the rivets have a cylindrical shape matching the shape of the indentations. The rivets can be sharpened to a point. The rivets can include a first piece formed of precious metal and a second piece formed of nickel or nickel alloy, wherein an end of the first piece is welded to an end of the second piece, and the second piece is welded to the base. Alternatively, the rivets can be formed entirely of the precious metal.

Abstract: A corona comprises a central electrode surrounded by an insulator, which is surrounded by a conductive component. The conductive component includes a shell and an intermediate part both formed of an electrically conductive material. The intermediate part is a layer of metal which brazes the insulator to the shell. An outer surface of the insulator presents a lower ledge, and the layer of metal can be applied to the insulator above the lower ledge prior to or after inserting the insulator into the shell. The conductive inner diameter is less than an insulator outer diameter directly below lower ledge such the insulator thickness increases toward the electrode firing end. The insulator outer diameter is also typically less than the shell inner diameter so that the corona igniter be forward-assembled.

Abstract: An igniter, such as a corona igniter for an internal combustion engine, and a method of manufacturing the igniter, are provided. The igniter includes an insulator with enlarged upper and lower end regions extending axially beyond opposite ends of a constrained, reduced diameter region of a shell through passage. The enlarged lower end region of the insulator is disposed axially outwardly of a lower end of the shell. The insulator is hermetically sealed to the shell and is permanently fixed against being removed axially outwardly from the shell. The method can include conforming the shell to the contour of the insulator by plastically deforming the shell, or casting the shell about the insulator. Alternatively, separate pieces of metal can be disposed around the insulator to form the shell which is conformed to the insulator.

Abstract: An igniter assembly comprising an ignition coil assembly connected to a firing end assembly by an extension, with a valve assembly disposed in a pressure chamber of the extension, is provided. The valve assembly includes a valve stem biased toward the ignition coil assembly by a spring to seal the pressure chamber. The valve assembly is used to evacuate contents from the pressure chamber by pressing the valve stem toward the spring and allowing contents of the pressure chamber to travel through and past the valve stem and out of the pressure chamber. The valve assembly is also used to fill the pressure chamber with an insulating medium by pressing the valve stem toward the spring and allowing the insulating medium to travel through and past the valve stem and into the pressure chamber after evacuating the contents out of the pressure chamber.

Abstract: A reversed-assembled corona igniter including an insulator, central electrode, and metal shell, wherein an outer diameter of the insulator increases adjacent a lower end of the metal shell to achieve an electrical advantage is provided. In addition, the insulator maintains strength because is not placed under tension during or after assembly, or once disposed in an engine. To achieve the increase in insulator outer diameter, the insulator includes a lower shoulder adjacent the shell firing end. An intermediate part, such as braze and/or a metal ring, is disposed between the insulator outer surface and the shell adjacent the shell firing end. To prevent tension in the insulator, the insulator can be supported at only one location between the insulator upper end and the insulator lower end, for example along the intermediate part.

Abstract: A corona comprises a central electrode surrounded by an insulator, which is surrounded by a conductive component. The conductive component includes a shell and an intermediate part both formed of an electrically conductive material. The intermediate part is a layer of metal which brazes the insulator to the shell. An outer surface of the insulator presents a lower ledge, and the layer of metal can be applied to the insulator above the lower ledge prior to or after inserting the insulator into the shell. The conductive inner diameter is less than an insulator outer diameter directly below the lower ledge such the insulator thickness increases toward the electrode firing end. The insulator outer diameter is also typically less than the shell inner diameter so that the corona igniter can be forward-assembled.