An ignition device for an internal combustion engine includes an ignition coil, a first switch, a secondary current adjuster, and controller. The ignition coil includes a primary coil, a core, and a secondary coil. The first switch switches an energized state of the primary coil between an ON state and an OFF state. The secondary current adjuster adjusts a current value of a secondary current flowing through the secondary coil. The controller controls the secondary current adjuster so that a current value of the secondary current in at least a part of a charging period of the ignition plug, which is a period from when the energized state of the primary coil is switched from the ON state to the OFF state by the first switch to when dielectric breakdown occurs in the ignition plug, becomes smaller than a peak value of the secondary current after the dielectric breakdown occurs.

Systems, apparatuses, and methods of controlling an ignitor are disclosed. A method includes: receiving, by a controller, fuel quality data regarding a fuel for a spark-ignition engine; determining, by the controller, a fuel quality metric based on the fuel quality data; and controlling, by the controller, an ignition energy characteristic of an ignitor in response to the fuel quality metric.

Systems, apparatuses, and methods of controlling an ignitor are disclosed. A method includes: receiving, by a controller, fuel quality data regarding a fuel for a spark-ignition engine; determining, by the controller, a fuel quality metric based on the fuel quality data; and controlling, by the controller, an ignition energy characteristic of an ignitor in response to the fuel quality metric.

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 ignition control system for an internal combustion engine includes a controller, which includes an IGT generating section and an IGW generating section and is connected to ignition devices through an IGT signal line and an IGW signal line. The IGW signal line includes bifurcated portions, which sequentially bifurcate from a common main signal line. The bifurcated portions each correspond to one of the ignition devices and include a branched line, which is connected to an energy supply circuit inside the corresponding ignition device.

An ignition device for an internal combustion engine includes an ignition coil, a first switch, a secondary current adjuster, and controller The ignition coil includes a primary coil, a core, and a secondary coil. The first switch switches an energized state of the primary coil between an ON state and an OFF state. The secondary current adjuster adjusts a current value of a secondary current flowing through the secondary coil. The controller controls the secondary current adjuster so that a current value of the secondary current in at least a part of a charging period of the ignition plug, which is a period from when the energized state of the primary coil is switched from the ON state to the OFF state by the first switch to when dielectric breakdown occurs in the ignition plug, becomes smaller than a peak value of the secondary current after the dielectric breakdown occurs.

An ignition device for an internal combustion engine includes an ignition coil, a first switch, a secondary current adjuster, and controller The ignition coil includes a primary coil, a core, and a secondary coil. The first switch switches an energized state of the primary coil between an ON state and an OFF state. The secondary current adjuster adjusts a current value of a secondary current flowing through the secondary coil. The controller controls the secondary current adjuster so that a current value of the secondary current in at least a part of a charging period of the ignition plug, which is a period from when the energized state of the primary coil is switched from the ON state to the OFF state by the first switch to when dielectric breakdown occurs in the ignition plug, becomes smaller than a peak value of the secondary current after the dielectric breakdown occurs.

An ignition apparatus for internal combustion engine includes an ignition coil in which a main primary coil and an auxiliary primary coil are magnetically coupled with a secondary coil that is connected to a spark plug. In the ignition apparatus, a main ignition circuit unit controls energization of the main primary coil and performs a main ignition operation in which a spark discharge is generated in the spark plug. An energy supply circuit unit controls energization of the auxiliary primary coil and performs an energy supply operation in which a current that has the same polarity as a secondary current that flows through the secondary coil as a result of the main ignition operation is superimposed on the secondary current. The auxiliary primary coil includes a plurality of auxiliary-primary-coil portions. The energy supply circuit unit performs the energy supply operation using one or more of the plurality of auxiliary-primary-coil portions.

An ignition control system for an internal combustion engine includes a controller, which includes an IGT generating section and an IGW generating section and is connected to ignition devices through an IGT signal line and an IGW signal line. The IGW signal line includes bifurcated portions, which sequentially bifurcate from a common main signal line. The bifurcated portions each correspond to one of the ignition devices and include a branched line, which is connected to an energy supply circuit inside the corresponding ignition device.