Methods and systems are provided for an engine having a pre-chamber ignition system. In one example, a method may include adjusting a valve coupled between a pre-chamber of an engine cylinder and a main chamber of the engine cylinder between a fully open position and a fully closed position based on whether pre-chamber ignition is desired or direct spark ignition is desired. In this way, the engine may be operated with direct spark ignition during conditions when pre-chamber combustion has reduced stability without including additional spark plugs and air injectors.

An ignition device includes: a high frequency power source; a first device having inductance; a second device having capacitance; a discharge GAP; and a shield device which covers a connection portion between the first device and the second device, and is connected to the ground. The high frequency power source supplies AC power to the discharge GAP by using a resonance circuit composed of the first device and the second device, and ignites fuel by discharge plasma generated in the discharge GAP. In the ignition device, the first device, the second device, the connection portion, and the shield device are arranged in the same package and are sealed with an insulating substance.

An ignition device includes: a high frequency power source; a first device having inductance; a second device having capacitance; a discharge GAP; and a shield device which covers a connection portion between the first device and the second device, and is connected to the ground. The high frequency power source supplies AC power to the discharge GAP by using a resonance circuit composed of the first device and the second device, and ignites fuel by discharge plasma generated in the discharge GAP. In the ignition device, the first device, the second device, the connection portion, and the shield device are arranged in the same package and are sealed with an insulating substance.

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.

An ignition device for igniting an air/fuel mixture in a combustion chamber, in particular of an internal combustion engine, having a spark plug which has a first electrode and a second electrode, having a high voltage source for generating an electrical high voltage pulse at an output of the high voltage source, and having a high frequency voltage source for generating an electrical high frequency alternating voltage at an output of the high frequency voltage source, wherein the output of the high voltage source is connected electrically to the first electrode of the spark plug via a first electrical conduction path in such a way that the high voltage pulse is present at the first electrode, wherein the output of the high frequency voltage source is connected electrically to the second electrode via a second electrical conduction path in such a way that the high frequency alternating voltage is present at the second electrode.

An ignition device for igniting an air/fuel mixture in a combustion chamber, in particular of an internal combustion engine, having a spark plug which has a first electrode and a second electrode, having a high voltage source for generating an electrical high voltage pulse at an output of the high voltage source, and having a high frequency voltage source for generating an electrical high frequency alternating voltage at an output of the high frequency voltage source, wherein the output of the high voltage source is connected electrically to the first electrode of the spark plug via a first electrical conduction path in such a way that the high voltage pulse is present at the first electrode, wherein the output of the high frequency voltage source is connected electrically to the second electrode via a second electrical conduction path in such a way that the high frequency alternating voltage is present at the second electrode.

The subject matter of this specification can be embodied in, among other things, a method that includes receiving a collection of measurements of electric current amplitude in a primary winding of an engine ignition system having the primary winding and a spark plug, identifying an ignition start time, identifying an inflection point based on the plurality of measurements, determining an inflection point time representative of a time at which the identified inflection point occurred, determining a spark start time based on an amount of time between the ignition start time and the inflection point time, and providing a signal indicative of the spark start time.

To provide an ignition apparatus which can turn on and off the sub primary coil according to extension degree of the discharge path of the spark discharge. An ignition apparatus is provided with an ignition coil that is provided with a main primary coil, a sub primary coil which generates energization magnetic flux of a direction opposite to the energization magnetic flux of the main primary coil, and a secondary coil which is magnetically coupled with the main primary coil and the sub primary coil and supplies spark discharge energy to a spark plug; and after turning off energization to the main primary coil, based on a detection value of terminal voltage of the main primary coil, turns on and off the sub switch circuit to turn on and off energization to the sub primary coil and additionally supply spark discharge energy to the secondary coil.

The ignition apparatus includes: an ignition plug; a plurality of high voltage devices each configured to generate the high voltage and apply the high voltage between the first electrode and the second electrode; a leakage current detection device configured to detect a leakage current flowing between the first electrode and the second electrode; and a control device configured to control respective operations of the plurality of high voltage devices and the leakage current detection device. When the control device determines that leakage is present between the first electrode and the second electrode based on the leakage current detected by the leakage current detection device, the control device causes each of the plurality of high voltage devices to apply the high voltage between the first electrode and the second electrode at the same period.