In an ignition control device for an internal-combustion engine, signal separation circuitry receives and separates an ignition control signal that is an integrated signal of a main ignition signal for controlling the main ignition operation, an energy input signal for controlling the energy input operation, and a target secondary current command signal. The ignition control signal is formed of a first signal and a second signal that are pulsed signals. The signal separation circuitry is configured to generate, from the ignition control signal, the main ignition signal based on rising edges of the first signal and the second signal as pulse-waveform information of the first signal and the second signal, generate the energy input signal based on a pulse width of the second signal as pulse-waveform information of the second signal, and generate the target secondary current command signal based on pulse-waveform information of the first signal.

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.

A switch control circuit controls a switch element connected to a primary coil of an ignition coil in accordance with an ignition signal. The switch element includes a transistor and a protection element connected between a collector and gate of the transistor. The switch control circuit uses a voltage at a gate terminal controlling the transistor or a voltage corresponding to a collector current of the transistor as a detection voltage and generates a status detection signal corresponding to a change in the detection voltage.

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.

An ignition system includes a primary coil, a secondary coil, a first switch, a second switch, a third switch, a diode, and a switch control section. In the primary coil, a power supply is connected to a contact point between a first winding and a second winding. The secondary coil is magnetically coupled to the primary coil. The first switch is connected in series with the first winding. The second switch is connected in series with the second winding on the opposite side from the contact point. The third switch is connected in series with the second switch. The diode includes an anode connected between the second switch and the third switch and a cathode connected to the contact point. The switch control section controls opening and closing of each switch.

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.

An embodiment system for controlling an ignition coil includes a first ignition coil including a first primary coil and a first secondary coil, a second ignition coil including a second primary coil and a second secondary coil, a spark plug including a pair of electrodes configured to generate a spark discharge by a discharge current generated by the first ignition coil and the second ignition coil, and a controller configured to selectively perform a multi-stage ignition through the first ignition coil and the second ignition coil or a single-stage ignition through the first ignition coil or the second ignition coil depending on an operation region of an engine and, in response to a misfire occurring in the engine while performing the multi-stage ignition, to adjust a number of ignitions or a dwell time.

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 system and method for delivering spark to an engine is disclosed. In one example, a single conductor carries a spark signal that is indicative of a desired spark advance for a plurality of ignition coils. The system and method may reduce wiring complexity for spark plugs that are supplied energy via two ignition coils.

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.