An apparatus for igniting a combustible mixture. In one example, the apparatus can include a coaxial cavity resonator assembly in a combustion environment. The apparatus can also include an operational feedback system and a controller. The operational feedback system can measure at least one of a voltage value and a current value of the coaxial cavity resonator assembly in the combustion environment. The controller can be configured to determine a condition of the coaxial cavity resonator assembly and modulate operation of the coaxial cavity resonator assembly based at least in part on the determined condition.

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 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.

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.

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.

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 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.

An apparatus comprises a coaxial cavity resonator; a radio frequency power source coupled to the coaxial cavity resonator; a direct current power source coupled to the coaxial cavity resonator; a combustion process feedback module configured to sense a condition in a combustion environment by measuring a characteristic of the coaxial cavity resonator; and a controller configured to modulate operation of the coaxial cavity resonator based at least in part on combustion process feedback information from the combustion process feedback module.

An apparatus comprises a coaxial cavity resonator; a radio frequency power source coupled to the coaxial cavity resonator; a direct current power source coupled to the coaxial cavity resonator; a combustion process feedback module configured to sense a condition in a combustion environment by measuring a characteristic of the coaxial cavity resonator; and a controller configured to modulate operation of the coaxial cavity resonator based at least in part on combustion process feedback information from the combustion process feedback module.

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).