The invention relates to a method for operating an internal combustion engine with fuel which is combusted using a spark plug. According to the invention, the aging of the spark plug, in particular the aging of an electric resistor of the spark plug, is monitored during the operation of the internal combustion engine, wherein electromagnetic radiation of the spark plug is detected for monitoring purposes. The invention additionally relates to a controller for carrying out the method.

The invention relates to a method for operating an internal combustion engine with fuel which is combusted using a spark plug. According to the invention, the aging of the spark plug, in particular the aging of an electric resistor of the spark plug, is monitored during the operation of the internal combustion engine, wherein electromagnetic radiation of the spark plug is detected for monitoring purposes. The invention additionally relates to a controller for carrying out the method.

Provided is a stroke determination device which detects a secondary output from an ignition coil without using a high breakdown voltage element, and is capable of accurately establishing the stroke being carried out during an ignition operation of a four-stroke engine from the waveform of the detected secondary output. In the present invention, a secondary coil of an ignition coil is constituted from a first coil portion, and a second coil portion wound so as to have fewer windings than does the first coil portion and connected in series to the first coil portion. A tap is drawn out from a boundary part between both coil portions, the voltage at both ends of the second coil portion or the current flowing through the second coil portion is detected through the tap, and a parameter to be used in stroke determination is detected from the waveform of the detected voltage or current.

A method of detecting the breakdown voltage between the electrodes of a spark plug connected to an ignition coil for a cylinder ignition system, in an internal combustion engine, comprises a detection of an opening of the switch (105) on the primary winding (102) and a detection of a voltage on that primary winding (102), with the generation of a first signal (V.sub.1) representative of the voltage trend following the opening of the switch (105).

The first signal (V.sub.1) is then integrated and, following an identification of a breakdown at the ends of the spark plug (106), a breakdown voltage value is determined as a function of the value of the integrated signal at the time of the breakdown.

A method of detecting the breakdown voltage between the electrodes of a spark plug connected to an ignition coil for a cylinder ignition system, in an internal combustion engine, comprises a detection of an opening of the switch (105) on the primary winding (102) and a detection of a voltage on that primary winding (102), with the generation of a first signal (V.sub.1) representative of the voltage trend following the opening of the switch (105).

The first signal (V.sub.1) is then integrated and, following an identification of a breakdown at the ends of the spark plug (106), a breakdown voltage value is determined as a function of the value of the integrated signal at the time of the breakdown.

An ignition apparatus is provided which ignites a mixture of air and fuel gas by plasma to generate an initial flame. The apparatus includes: a spark plug that includes an inner conductor, a cylindrical outer conductor that holds the inner conductor thereinside, and a dielectric that is provided between the inner conductor and the outer conductor, and that generates plasma in a plasma formation space between the inner conductor and the outer conductor; an electromagnetic wave power supply that generates an electromagnetic wave to apply electromagnetic wave power to the spark plug; an evaluation section that evaluates a state of formation of the plasma; a determination section that determines a matching object of the electromagnetic wave based on an evaluation result by the evaluation section; and a coupled state control section that controls a matching condition of the electromagnetic wave so that the electromagnetic wave matches the matching object.

A method for monitoring an aircraft turboshaft engine including a vibration sensor capable of outputting a vibration signal and a spark plug. The method includes, based on the vibration signal output by the vibration sensor, a step of determining a level of vibration of the turboshaft engine as well as a step of determining an indicator of spark plug wear.

A method for monitoring an aircraft turboshaft engine including a vibration sensor capable of outputting a vibration signal and a spark plug. The method includes, based on the vibration signal output by the vibration sensor, a step of determining a level of vibration of the turboshaft engine as well as a step of determining an indicator of spark plug wear.

A barrier-discharge-type ignition apparatus that can accurately determine the application voltage, of a barrier ignition plug, that causes a non-ignition discharge to occur. In the barrier-discharge-type ignition apparatus, in a combustion assist control, the voltage difference between the one-period-prior application voltage and the present-period application voltage in the AC period is calculated based on an application voltage detected by a voltage detection circuit; then, it is determined whether or not a discharge exists in the barrier ignition plug, based on the comparison between the voltage difference and a preliminarily set discharge determination threshold value.

Ignitability of a fuel by a spark plug is improved while an increase in the number of ignition coils is suppressed. A control device for an internal combustion engine includes an ignition control unit 83 which controls energization of an ignition coil 300a and an ignition coil 300b which each provide electric energy to a spark plug which discharges in a cylinder of an internal combustion engine to ignite a fuel, and a discharge amount detection unit which detects an inter-electrode voltage of the spark plug. After the ignition control unit 83 discharges the spark plug using the electric energy of the ignition coil 300a, the ignition control unit estimates a voltage which is supply-able from the ignition coil 300a to the spark plug, and controls energization of the ignition coil so as to supply the electric energy of the second ignition coil 300b to the spark plug when a difference d between the estimated supply-able voltage and a required voltage based on the voltage detected by the discharge amount detection unit is equal to or less than a predetermined threshold value.