An ignition apparatus is provided which ignites a mixture of air and fuel gas by plasma to generate an initial flame. The apparatus includes: a spark plug that includes an inner conductor, a cylindrical outer conductor that holds the inner conductor thereinside, and a dielectric that is provided between the inner conductor and the outer conductor, and that generates plasma in a plasma formation space between the inner conductor and the outer conductor; an electromagnetic wave power supply that generates an electromagnetic wave to apply electromagnetic wave power to the spark plug; an evaluation section that evaluates a state of formation of the plasma; a determination section that determines a matching object of the electromagnetic wave based on an evaluation result by the evaluation section; and a coupled state control section that controls a matching condition of the electromagnetic wave so that the electromagnetic wave matches the matching object.

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.

The present disclosure relates to gas turbine engine operation in which an igniter assembly is provided with an electrical energy input (e.g., an electrical waveform) that is configured to increase a likelihood of igniting a fuel-air mixture surrounding the igniter assembly. In certain embodiments, the igniter assembly is supplied with an augmented electrical waveform that may reduce a quantity of sparks generated by the igniter assembly before successful light-off (e.g., ignition) of the fuel-air mixture is achieved (e.g., as compared to a quantity of sparks generated to achieve ignition by an igniter assembly that receives an electrical energy input in the form of a conventional electrical waveform). Accordingly, the augmented electrical waveform may reduce wear (e.g., via oxidation) on electrodes of the igniter assembly, such as a primary electrode (e.g., a center electrode) and a secondary electrode (e.g., an outer shell electrode) disposed about the primary electrode.

A combustor for a gas turbine system includes a combustor casing having an interior-establishing wall, and a chamber extending to the interior-establishing wall. In addition, the combustor includes an igniter assembly disposed within the chamber such that a tip of the igniter assembly is positioned radially outwardly from the interior-establishing wall. The igniter assembly includes a first electrode, a second electrode, and an insulator. In addition, the first electrode, the second electrode, and the insulator form a cavity, the second electrode forms an outlet passage extending from the cavity, a maximum cross-sectional area of the cavity is greater than a minimum cross-sectional area of the outlet passage, and the first electrode and the second electrode are configured to ionize gas within the cavity in response to an electrical current applied to the first electrode or to the second electrode.

A combustor for a gas turbine system includes a combustor casing having an interior-establishing wall, and a chamber extending to the interior-establishing wall. In addition, the combustor includes an igniter assembly disposed within the chamber such that a tip of the igniter assembly is positioned radially outwardly from the interior-establishing wall. The igniter assembly includes a first electrode, a second electrode, and an insulator. In addition, the first electrode, the second electrode, and the insulator form a cavity, the second electrode forms an outlet passage extending from the cavity, a maximum cross-sectional area of the cavity is greater than a minimum cross-sectional area of the outlet passage, and the first electrode and the second electrode are configured to ionize gas within the cavity in response to an electrical current applied to the first electrode or to the second electrode.

A spark plug has a specific direction orthogonal to an axial direction of a spark plug; the specific direction has opposing front directional side and rear directional side; the housing has a tip surface having a front end in the front side of the specific direction and a rear end in the rear side, the tip surface has a tip inclined surface inclined toward the tip end of the spark plug from the front end to the rear end of the tip surface. The tip inclined surface has a rear end in the specific direction, the insulator having a front end of the specific direction, the rear end is located to be closer to the tip end of the spark plug than the front end of the tip surface is, and to be more rearward than the front end of the insulator in the rear side of the specific direction.

A spark plug has a specific direction orthogonal to an axial direction of a spark plug; the specific direction has opposing front directional side and rear directional side; the housing has a tip surface having a front end in the front side of the specific direction and a rear end in the rear side, the tip surface has a tip inclined surface inclined toward the tip end of the spark plug from the front end to the rear end of the tip surface. The tip inclined surface has a rear end in the specific direction, the insulator having a front end of the specific direction, the rear end is located to be closer to the tip end of the spark plug than the front end of the tip surface is, and to be more rearward than the front end of the insulator in the rear side of the specific direction.

A pre-chamber is formed between the front end of a spark plug attached to the cylinder head and a thin pre-chamber wall sticking out from the inside wall surface of the cylinder head to the inside of a main combustion chamber. The communication holes communicating the inside of the pre-chamber and the inside of the main combustion chamber are formed inside the thin pre-chamber wall. The thin pre-chamber wall is formed into a shape with a cross-sectional area gradually decreasing from the inside wall surface of the cylinder head toward the inside of the main combustion chamber such as a conical shape, frustoconical shape, polygonal conical shape, or polygonal frustoconical shape. A ground side electrode portion of the spark plug is positioned inside the gas pocket, and a discharge is caused between the center electrode sticking out from the front end of the center electrode insulator and the ground side electrode portion at the time of ignition.

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.

An ignition control system includes a spark plug including a cylindrical ground electrode, a cylindrical insulator having a protruding portion held inside the ground electrode and protruding toward a tip side the spark plug relative to the ground electrode, and a center electrode held inside the insulator and exposed from the insulator, an ignition coil including a primary coil and a secondary coil, and a primary current control unit performing creeping discharge control for generating a creeping discharge along a surface of the insulator, and air discharge transition control for stopping the creeping discharge occurring in the spark plug after the creeping discharge control is performed, and cutting off primary current after a discharge stop period ends, in one combustion cycle of the engine.