A system and method for detecting resonant frequency of a corona igniter concurrent with operation of the corona igniter is provided. The method includes providing a plurality of pulses of energy to the corona igniter, each having a pulse duration and spaced from one another by a deadtime duration during which no energy is provided to the corona igniter. Each pulse duration is ceased before current flowing in the corona igniter crosses zero, and each zero crossing of the current occurs during one of the deadtime durations. The next pulse of energy is provided to the corona igniter in response to the zero crossing of the current. A resonant frequency value is then obtained based on a sum of the pulse and deadtime durations of two consecutive cycles, or the time between zero crossings. The resonant frequency values become more accurate over time, and the drive frequency is adjusted accordingly.

An ignition system for an engine includes a sparkplug, ignition circuitry electrically connected to the sparkplug, and an ignition control unit structured to energize the ignition circuitry to fire the sparkplug at an ignition timing, detect a fault condition caused by an abnormal response of the sparkplug to the energizing, and to energize the ignition circuitry to dry fire the sparkplug at an offset timing such as during an exhaust, stroke based on the detection of the fault condition. Dry firing the sparkplug reduces a break down voltage required to subsequently fire the sparkplug and extends sparkplug service life.

An ignition system for an engine includes a sparkplug, ignition circuitry electrically connected to the sparkplug, and an ignition control unit structured to energize the ignition circuitry to fire the sparkplug at an ignition timing, detect a fault condition caused by an abnormal response of the sparkplug to the energizing, and to energize the ignition circuitry to dry fire the sparkplug at an offset timing such as during an exhaust, stroke based on the detection of the fault condition. Dry firing the sparkplug reduces a break down voltage required to subsequently fire the sparkplug and extends sparkplug service life.

A method of verifying a cylinder deactivation mode on an engine is provided. The method can include activating an ignition device in a deactivated cylinder during an exhaust stroke of the deactivated cylinder. The method can include measuring a voltage of the ignition device. The method can include comparing at least one of an amplitude and a timing of a measured spike of the voltage against a baseline voltage spike. The method can include indicating a status of the deactivation mode based on the comparison against the baseline voltage spike.

Even when detecting the primary voltage of the primary coil side, without detecting the secondary voltage of the secondary coil side of high voltage, it is desired to provide a discharge state detecting apparatus of an internal combustion engine which can detect a spark discharge state with good accuracy, by reducing influences of the discharge current and the resistance component of the discharge path of the secondary coil side, which are generated in the primary voltage. A discharge state detecting apparatus of an internal combustion engine performs correction which reduces a signal component generated by the secondary current in the ignition coil from the primary voltage detected by the primary voltage detector, based on the detected secondary current, and outputs a primary voltage after correction; and determines a spark discharge state based on the primary voltage after correction.

A device registers an On state of a drive motor of a tool. A changing magnetic flux is produced in the On state of the drive motor. First and second peak hold detectors generate upper and lower peak signals from induced voltage output signals. An evaluation device is configured to form a difference from the generated upper peak signal and the generated lower peak signal, and compare the formed difference with an adjustable threshold value in order to determine the On state of the drive motor when the threshold value is reached or exceeded.

Even when detecting the primary voltage of the primary coil side, without detecting the secondary voltage of the secondary coil side of high voltage, it is desired to provide a discharge state detecting apparatus of an internal combustion engine which can detect a spark discharge state with good accuracy, by reducing influences of the discharge current and the resistance component of the discharge path of the secondary coil side, which are generated in the primary voltage. A discharge state detecting apparatus of an internal combustion engine performs correction which reduces a signal component generated by the secondary current in the ignition coil from the primary voltage detected by the primary voltage detector, based on the detected secondary current, and outputs a primary voltage after correction; and determines a spark discharge state based on the primary voltage after correction.

A method is described for determining the resistance temperature characteristic of a ceramic glow plug, wherein the glow plug is heated at a specified power, wherein before the heating it is first determined whether the glow plug is an aged glow plug, and then, if the glow plug has not been detected as an aged glow plug, the glow plug is heated at a first specified power and the resistance value thereby achieved is assigned to a temperature that is anticipated to be the final temperature when heating a factory-outlet glow plug at this first power, or if the glow plug has been detected as an aged glow plug, the glow plug is heated at a reduced power which is smaller than the first power, and the resistance value achieved thereby is assigned to the same temperature that is also anticipated when heating a factory-outlet glow plug at the first power.

A method is described for determining the resistance temperature characteristic of a ceramic glow plug, wherein the glow plug is heated at a specified power, wherein before the heating it is first determined whether the glow plug is an aged glow plug, and then, if the glow plug has not been detected as an aged glow plug, the glow plug is heated at a first specified power and the resistance value thereby achieved is assigned to a temperature that is anticipated to be the final temperature when heating a factory-outlet glow plug at this first power, or if the glow plug has been detected as an aged glow plug, the glow plug is heated at a reduced power which is smaller than the first power, and the resistance value achieved thereby is assigned to the same temperature that is also anticipated when heating a factory-outlet glow plug at the first power.

A method for detecting glow plug replacement or an aging glow plug. The glow plugs are heated and monitored. When a threshold value is reached for a first glow plug, a first value of a temperature-dependent variable is measured for all other glow plugs and is stored as reference values associated with the first glow plug. This process is repeated until reference values associated with each glow plug have been determined and stored for each glow plug. The process is repeated to determine a set of comparative values. The comparative values are compared with the reference values. A deviation of a comparative from a reference value of less than a specified tolerance value is considered an agreement. The inventive process concludes which of the glow plugs of the engine are unaltered and which have a resistance-temperature characteristic that has been altered to an extent indicating replacement, aging or a defect.