An engine ignition system for a spark-ignited engine includes a sparkplug and a control system having primary ignition circuitry, secondary ignition circuitry coupled with electrodes of the sparkplug, and sensing circuitry. A control device determines a timing of spark production based on a pattern of varying of an electrical property in the primary ignition circuitry. An inflection point in a sensed current signal may be detected to determine the timing.

An engine ignition system for a spark-ignited engine includes a sparkplug and a control system having primary ignition circuitry, secondary ignition circuitry coupled with electrodes of the sparkplug, and sensing circuitry. A control device determines a timing of spark production based on a pattern of varying of an electrical property in the primary ignition circuitry. An inflection point in a sensed current signal may be detected to determine the timing.

A method for controlling a corona ignition system in which a corona discharge is produced at an ignition electrode by exciting a resonating circuit with an AC voltage produced by a high-frequency generator. The AC voltage is adjusted to a target value depending on an operating state of the engine. Combustion onset is determined by evaluating an electrical variable of the resonating circuit and the target value of the AC voltage is reduced by a predefined value following a predefined number of engine cycles or a predefined operating period. The determined combustion onset is evaluated in one or more engine cycles. The target value for the momentary engine operating state is then increased if, by evaluation of the combustion onset, it is found that a predefined requirement is no longer met. Otherwise, the reduced target value is stored as a new target value for the momentary engine operating state.

A method for controlling a corona ignition system in which a corona discharge is produced at an ignition electrode by exciting a resonating circuit with an AC voltage produced by a high-frequency generator. The AC voltage is adjusted to a target value depending on an operating state of the engine. Combustion onset is determined by evaluating an electrical variable of the resonating circuit and the target value of the AC voltage is reduced by a predefined value following a predefined number of engine cycles or a predefined operating period. The determined combustion onset is evaluated in one or more engine cycles. The target value for the momentary engine operating state is then increased if, by evaluation of the combustion onset, it is found that a predefined requirement is no longer met. Otherwise, the reduced target value is stored as a new target value for the momentary engine operating state.

A control apparatus, which is for an internal combustion engine with a spark plug having a center electrode and a ground electrode disposed so as to form a spark discharge gap therebetween, includes a voltage applying section for applying a voltage to the spark discharge gap, a constant-voltage path including a constant-voltage element parallel-connected to the spark discharge gap of the spark plug for preventing the spark discharge gap from being applied with a voltage higher than a set voltage, and an operation control circuit for controlling an operating condition of the internal combustion engine. The operation control circuit is configured to measure a current-flowing time during which a current flows through the constant-voltage path when a voltage higher than the set voltage is applied to the constant-voltage path, and change the operating condition of the internal combustion engine in accordance with the measured current-flowing time.

A control apparatus, which is for an internal combustion engine with a spark plug having a center electrode and a ground electrode disposed so as to form a spark discharge gap therebetween, includes a voltage applying section for applying a voltage to the spark discharge gap, a constant-voltage path including a constant-voltage element parallel-connected to the spark discharge gap of the spark plug for preventing the spark discharge gap from being applied with a voltage higher than a set voltage, and an operation control circuit for controlling an operating condition of the internal combustion engine. The operation control circuit is configured to measure a current-flowing time during which a current flows through the constant-voltage path when a voltage higher than the set voltage is applied to the constant-voltage path, and change the operating condition of the internal combustion engine in accordance with the measured current-flowing time.

An igniter that includes switch element and switch control device for controlling the switch element depending on ignition signal. The switch control device includes a determination stage that compares voltage associated with the ignition signal with a predetermined voltage to generate a determination signal, a driving stage that controls ON/OFF operations of the switch element depending on the determination signal, a timer circuit that asserts a conduction protection signal when state where the determination signal becomes an assert level corresponding to an ON operation of the switch element continues for predetermined time, a time-varying voltage generating circuit that generates time-varying voltage over time in response to the assertion of the conduction protection signal, and an amplifier that changes the voltage of a control terminal of the switch element such that detection voltage associated with coil current flowing in the switch element is close to the time-varying voltage.

A misfire determination device of an engine in which explosion occurs at unequal intervals, the engine including a plurality of cylinders and a crankshaft which is angularly displaced at a different angle between expansion strokes, is configured to calculate generated torque correlation amount correlated with generated torque, based on an angular position signal of the crankshaft, and perform misfire determination, based on an average value of the generated torque correlation amount in an interval less than one cycle of the engine, at an angular position of the crankshaft which is different from an angular position of the crankshaft at an ignition timing.

A misfire determination device of an engine in which explosion occurs at unequal intervals, the engine including a plurality of cylinders and a crankshaft which is angularly displaced at a different angle between expansion strokes, is configured to calculate generated torque correlation amount correlated with generated torque, based on an angular position signal of the crankshaft, and perform misfire determination, based on an average value of the generated torque correlation amount in an interval less than one cycle of the engine, at an angular position of the crankshaft which is different from an angular position of the crankshaft at an ignition timing.

An internal combustion engine is described and includes a combustion chamber formed by cooperation of a cylinder bore formed in a cylinder block, a cylinder head and a piston. A plasma ignition controller is electrically connected to a groundless barrier discharge plasma igniter that includes a tip portion disposed to protrude into the combustion chamber. A current sensor is disposed to monitor secondary current flow between the plasma ignition controller and the groundless barrier discharge plasma igniter. The plasma ignition controller is disposed to execute a plasma discharge event. A controller is disposed to monitor a magnitude of the secondary current flow via the current sensor during the plasma discharge event. The controller includes an instruction set executable to evaluate integrity of the groundless barrier discharge plasma igniter based upon the magnitude of the secondary current flow during the plasma discharge event.