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.

A high-frequency discharge ignition device includes a current supply device which supplies an AC current to a spark discharge path formed in a gap of an ignition plug, a control device which controls the operation of the current supply device, and a voltage detection device which outputs a signal of a section where a magnetic induction voltage of a primary coil generated after a switch element of an ignition coil device is placed in a shutoff state exceeds a predetermined voltage, and the control device determines the timing when the spark discharge path has been formed in the gap of the ignition plug according to an output signal of the voltage detection device and operates the current supply device based on the timing when the spark discharge path has been formed in the gap of the ignition plug to supply the AC current to the spark discharge path.

A high-frequency discharge ignition device includes a current supply device which supplies an AC current to a spark discharge path formed in a gap of an ignition plug, a control device which controls the operation of the current supply device, and a voltage detection device which outputs a signal of a section where a magnetic induction voltage of a primary coil generated after a switch element of an ignition coil device is placed in a shutoff state exceeds a predetermined voltage, and the control device determines the timing when the spark discharge path has been formed in the gap of the ignition plug according to an output signal of the voltage detection device and operates the current supply device based on the timing when the spark discharge path has been formed in the gap of the ignition plug to supply the AC current to the spark discharge path.

An ignition device includes a spark plug, a measurement value detector, an electrical breakdown determiner, an AC voltage applying section, and a first changing section. The measurement value detector includes primary and secondary coils, and detects at least one measurement value among an ignition coil, a primary current, a primary voltage, a secondary current, and a secondary voltage. The electrical breakdown determiner determines whether a discharge has become an electrical breakdown state based on the measurement value. The AC voltage applying section applies an AC voltage of a first predetermined frequency that causes voltage resonance to the primary coil. The first changing section changes the frequency of the AC voltage to a second predetermined frequency that can maintain the electrical breakdown state and is lower in frequency than the first predetermined frequency when it is determined that the discharge has become the electrical breakdown state.

In a general aspect, an apparatus can include an insulated-gate bipolar transistor device (IGBT), a gate driver circuit (driver) coupled with a gate terminal of the IGBT and a low-resistance switch device coupled between an emitter terminal of the IGBT and an electrical ground terminal, the low-resistance switch device being coupled with the electrical ground terminal via a resistor. The apparatus can also include a current sensing circuit coupled with the driver and a current sense signal line coupled with the current sensing circuit and a current sense node, the current sense node being disposed between the low-resistance switch device and the resistor. The apparatus can further include a control circuit configured, when the driver is off, to detect, based on a voltage on the current sense node, when a current through the resistor is above a threshold value and disable the IGBT in response to the detection.

In a general aspect, an apparatus can include an insulated-gate bipolar transistor device (IGBT), a gate driver circuit (driver) coupled with a gate terminal of the IGBT and a low-resistance switch device coupled between an emitter terminal of the IGBT and an electrical ground terminal, the low-resistance switch device being coupled with the electrical ground terminal via a resistor. The apparatus can also include a current sensing circuit coupled with the driver and a current sense signal line coupled with the current sensing circuit and a current sense node, the current sense node being disposed between the low-resistance switch device and the resistor. The apparatus can further include a control circuit configured, when the driver is off, to detect, based on a voltage on the current sense node, when a current through the resistor is above a threshold value and disable the IGBT in response to the detection.

A system and method for providing multiple commands to an ignition coil driver circuit to provide spark, ion signal integration, and ignition coil shunting during a cycle of a cylinder is presented. In one example, multiple voltage pulses are provided over a single conductor communication link. The voltage pulses provide encoded instructions for ignition timing, ignition coil shunting, and ion signal integration.

A system and method for providing multiple commands to an ignition coil driver circuit to provide spark, ion signal integration, and ignition coil shunting during a cycle of a cylinder is presented. In one example, multiple voltage pulses are provided over a single conductor communication link. The voltage pulses provide encoded instructions for ignition timing, ignition coil shunting, and ion signal integration.

An internal combustion engine control apparatus includes: an ignition coil including a primary coil and a secondary coil that are magnetically coupled to each other; a first switch element for turning on and off a current to the primary coil; and a spark plug, for igniting an air-fuel mixture in an internal combustion engine by using a spark discharge caused by switching the first switch element from the ON state to the OFF state. The internal combustion engine control apparatus is configured to: determine occurrence of one of an abnormality in a discharge voltage and a misfire of the spark plug, when the calculated time duration in which a voltage of the primary coil after the switching of the first switch element from the ON state to the OFF state is above a predetermined comparison reference voltage does not fall within an allowable range.

An internal combustion engine control apparatus includes: an ignition coil including a primary coil and a secondary coil that are magnetically coupled to each other; a first switch element for turning on and off a current to the primary coil; and a spark plug, for igniting an air-fuel mixture in an internal combustion engine by using a spark discharge caused by switching the first switch element from the ON state to the OFF state. The internal combustion engine control apparatus is configured to: determine occurrence of one of an abnormality in a discharge voltage and a misfire of the spark plug, when the calculated time duration in which a voltage of the primary coil after the switching of the first switch element from the ON state to the OFF state is above a predetermined comparison reference voltage does not fall within an allowable range.