An ignition system and a method for a spark-ignition combustion engine having a high-frequency plasma-augmented ignition spark, the spark ignition of the fuel being realized by at least one spark plug associated with a combustion chamber of the combustion engine. The spark plug has a prechamber having at least one opening via which the prechamber communicates with the combustion chamber on the fuel side, so that the ignition spark in the prechamber, into which the high-frequency plasma can be injected, induces the plasma-augmented spark ignition of the fuel in the prechamber.

A corona igniter including a hermetic combustion seal between an insulator and center electrode is provided. The combustion seal includes a metallic coating, such as a nickel-based layer applied to a layer of molybdenum-manganese, and the metallic coating is disposed on the insulator inner surface. Optionally, a shot of copper-based powder can be disposed on a head of the center electrode. The center electrode and/or the copper-based powder is then brazed to the metallic coating on the inner surface of the insulator. The process can include applying the metallic coating to the inner surface while applying a metal coating to an outer surface of the insulator. The method further includes brazing the center electrode and/or the copper-based powder to the metallic coating on the inner surface while brazing the metal coating on the outer surface to a metal shell.

A corona igniter including a hermetic combustion seal between an insulator and center electrode is provided. The combustion seal includes a metallic coating, such as a nickel-based layer applied to a layer of molybdenum-manganese, and the metallic coating is disposed on the insulator inner surface. Optionally, a shot of copper-based powder can be disposed on a head of the center electrode. The center electrode and/or the copper-based powder is then brazed to the metallic coating on the inner surface of the insulator. The process can include applying the metallic coating to the inner surface while applying a metal coating to an outer surface of the insulator. The method further includes brazing the center electrode and/or the copper-based powder to the metallic coating on the inner surface while brazing the metal coating on the outer surface to a metal shell.

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.

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.

A spark plug includes: a central electrode extending from a front end side to a rear end side along an axis; an insulator including a front end section formed to be a bottomed tube surrounding a tip of the central electrode; a metal shell shaped to be tubular and structured to support the insulator such that the front end section of the insulator projects to the front end side from a front end section of the metal shell; and a plurality of ground electrodes each of which includes a first end forming a discharge gap with the front end section of the insulator and includes a second end connected to the front end section of the metal shell. The plurality of ground electrodes include a pair of ground electrodes different from each other in size of their discharge gaps.

An ignition device ignites a mixture of air and fuel gas by plasma to generate an initial flame. The ignition device includes a spark plug having an inner conductor, a cylindrical outer conductor that holds the inner conductor inside, and a dielectric provided between the inner conductor and the outer conductor, and the spark plug configured to emit an electromagnetic wave to a plasma formation space between the inner conductor and the outer conductor to generate a plasma. The ignition device includes an electromagnetic wave power supply that generates the electromagnetic wave by inputting the electromagnetic wave power Ps to the spark plug and a power supply control unit that controls the electromagnetic wave power supply. The electromagnetic wave power supply is configured to generate high frequency power at a number of different frequencies. The power supply control unit outputs at least one of the plurality of high frequency powers generated by the electromagnetic wave power supply as the electromagnetic wave power.

An ignition device according to the present invention includes: an ignition plug, which includes a first electrode, a second electrode, and a dielectric body arranged between the electrodes; an AC power supply configured to generate an AC voltage to be applied between the electrodes; a thermal plasma detection portion configured to output a thermal plasma occurrence signal when thermal plasma has occurred between the electrodes; and an application time period determination portion configured to determine an application time period for the AC voltage during one cycle of the internal combustion engine in advance before the application, and when the thermal plasma occurrence signal is received while the AC voltage is being applied based on the application time period, change the application time period so as to shorten the application time period.

The invention relates to a spark plug (100) for an internal combustion engine, in particular having a high frequency ignition system, having a central electrode (28; 128), a ground electrode (12; 112) and an electrical insulator (18; 118) arranged between the central electrode (28; 128) and the ground electrode (12; 112), wherein a central electrode connecting point (26; 126) for electrically connecting the central electrode (28; 128) to an ignition system is provided on the insulator (18; 118), wherein the central electrode (28; 128) and the ground electrode (12; 112) project beyond the insulator (18; 118) at an axial end (114) of the spark plug (100) and each form, with a part projecting axially beyond the insulator (18; 118), a central electrode end (140) and a ground electrode end (142), wherein the central electrode end (140) and the ground electrode end (142) are arranged and embodied in such a way that an axial region (170) of a gap (146) is formed between them in an axial direction, wherein the axial region (170) of the gap (146) is spaced apart from the insulator (18; 118), wherein at least one additional electrode (150) is provided which projects beyond the insulator (118) at the axial end (114) of the spark plug (100) and forms, with a part which projects axially beyond the insulator (118), an additional electrode end (154). In this case the additional electrode (150) is arranged electrically insulated from the ground electrode (112) and the central electrode (128), on the spark plug (100), wherein the additional electrode end (154) projects into the axial region (170) of the gap (146) between the central electrode end (140) and the ground electrode end (142) or is arranged into a region (170) of the gap (146) which is radially adjacent to the axial region (170) of the gap (146), and as a result divides the gap (146) into two ignition spark end gaps (156, 166).

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.