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.

An igniter includes a switch element with input, output control electrodes, a first lead in contact with the input electrode and connected to a primary coil of an ignition coil, a second lead that is grounded, a third lead spaced apart from the first and second leads, a first bonding wire connecting the output electrode and the third lead, a second bonding wire connecting the third lead and the second lead, and a control IC that drives the switch element based on an ignition instruction signal from an engine control unit. The control IC generates an ignition confirmation signal based on the voltage of the third lead, and outputs the signal to the engine control unit.

An ignition system includes a controller which controls two stagesto provide current to a spark plug. The stages include a first transformer including a first primary winding and a first secondary winding and a second transformer including a second primary winding and a second secondary winding. A switch is electrically connected between a supply high side and the high side of the first primary winding. A second switch is electrically connected between the first primary winding and the power supply low side supply. A third switch is connected between the junction of the switch and high side end of the first inductor and a point between the low side of the second primary winding and low side supply. A fourth switch is located between the low side of the second primary winding and the point. A fifth switch is located between the point and low side supply.

Approaches for controlling dwell time in the ignition system of an internal combustion engine are provided. In one example, a method may include adjusting dwell based on engine operating conditions and further adjusting dwell in a manner proportional to existent spark plug conditions. By constantly assessing spark plug condition during operating of the internal combustion engine, premature wear of the spark plug may be prevented leading to an extension in the service life of spark plug and other ignition system components.

Methods and systems are provided for determining an ignition coil dwell time based on an estimated ignition coil temperature. In one example, a method may include estimating the ignition coil temperature based on heat transfer between engine and the ignition coil, heat transfer between ambient and the ignition coil, and internal resistive heating of the ignition coil.

A method for actuating a spark plug, in which the spark plug is assigned a first ignition coil and second ignition coil. Triggered by a start signal, the primary winding of the first ignition coil is charged, and the primary winding of the second ignition coil is charged with a delay D, for which 0D, by supplying a direct current, wherein, while each primary winding, is charged, the respective secondary winding is blocked; the primary current supplied to the primary windings is measured; after a period T, the primary winding of the first ignition coil is discharged, and with the delay D the primary winding of the second ignition coil is discharged; the secondary current flowing through the spark plug is measured; thereafter the primary windings of the first and second ignition coil start to be charged alternately when the secondary current falls below a threshold; the primary windings are discharged alternately when the primary current reaches an upper threshold; the above steps are repeated until the duration of discharge between two electrodes of the spark plug 1 reaches a predefined value Z.

An internal-combustion-engine combustion state detecting apparatus is configured in such a way as to include a circulation unit that short-circuits a primary winding so as to form a circulation path including the primary winding, while a spark discharge is produced in an ignition plug, and a circulation current control unit that controls a circulation current flowing in the circulation path and in such a way that based on an ion current detected by an ion current detection apparatus, the combustion state of an inflammable fuel-air mixture is detected.

Methods and systems are provided for determining an ignition coil dwell time based on an estimated ignition coil temperature. In one example, a method may include estimating the ignition coil temperature based on heat transfer between engine and the ignition coil, heat transfer between ambient and the ignition coil, and internal resistive heating of the ignition coil.

Methods and systems are provided for determining a type of spark plug fouling. In one example, a method may include differentiating spark plug fouling due to soot accumulation from spark plug fouling due to fuel additive accumulation based on a current on a control wire of the spark plug following application of a dwell command. Further, exhaust oxygen sensor degradation and/or exhaust catalyst degradation may be determined based on switching frequencies of one or more exhaust oxygen sensors and the type of spark plug fouling.

An internal-combustion-engine combustion state detecting apparatus is configured in such a way as to include a circulation unit that short-circuits a primary winding so as to form a circulation path including the primary winding, while a spark discharge is produced in an ignition plug, and a circulation current control unit that controls a circulation current flowing in the circulation path and in such a way that based on an ion current detected by an ion current detection apparatus, the combustion state of an inflammable fuel-air mixture is detected.