A method for determining a need for changing a spark plug of a combustion engine, comprising the following steps: monitoring a current flowing through the spark plug, analyzing the current and thereby determine a time interval that is indicative for the time between application of a voltage to the spark plug and formation of an arc discharge between electrodes of the spark plug, creating a signal indicative of the need to change the spark plug if the duration of the determined time interval is outside predefined bounds.

A method for determining a need for changing a spark plug of a combustion engine, comprising the following steps: monitoring a current flowing through the spark plug, analyzing the current and thereby determine a time interval that is indicative for the time between application of a voltage to the spark plug and formation of an arc discharge between electrodes of the spark plug, creating a signal indicative of the need to change the spark plug if the duration of the determined time interval is outside predefined bounds.

In order to test a semiconductor spark plug, a test method comprises a step consisting of depositing water on the head of the spark plug, between the two electrodes of same, so that the water forms a water meniscus covering the semiconductor element of the head, a step consisting of applying, between the first terminal and the second terminal of the spark plug, a voltage equal to the operating voltage of the spark plug, a step consisting of identifying at least a first characteristic of electric arcs induced between the electrodes during the application of the voltage, and a step consisting of determining the operational or defective character of the spark plug according to the first characteristic of the electric arcs. This test method is particularly reliable and does not require constraining provisions in order to ensure the safety of the operators implementing the method.

In order to test a semiconductor spark plug, a test method comprises a step consisting of depositing water on the head of the spark plug, between the two electrodes of same, so that the water forms a water meniscus covering the semiconductor element of the head, a step consisting of applying, between the first terminal and the second terminal of the spark plug, a voltage equal to the operating voltage of the spark plug, a step consisting of identifying at least a first characteristic of electric arcs induced between the electrodes during the application of the voltage, and a step consisting of determining the operational or defective character of the spark plug according to the first characteristic of the electric arcs. This test method is particularly reliable and does not require constraining provisions in order to ensure the safety of the operators implementing the method.

A device for monitoring a life condition of a spark igniter in a gas turbine ignition system. The device includes an evaluation circuit having circuit components that include a hold capacitor, a transistor, and an operational amplifier arranged to form a sample-and-hold circuit, wherein an igniter spark impulse signal is applied to an input node of the evaluation circuit causing the transistor to turn on and the hold capacitor to discharge for a duration of the igniter spark impulse signal, and wherein a discharged voltage at the hold capacitor is maintained and output by the operational amplifier, the discharged voltage representing the duration of the igniter spark impulse and indicating the life condition of the spark igniter.

A spark plug electrode wearing rate estimating method for a spark plug in which spark discharge occurs between two electrodes by application of voltage generated by an ignition coil, includes the step of estimating a wearing rate of a first electrode in one spark discharge based on a temperature of the first electrode, and a spark discharge voltage and supply energy from the ignition coil. The first electrode contains any one of Ir, Ru, W, and Ni as a main component.

A plurality of assemblies are prepared, and a predetermined voltage is applied to a center electrode of each of the plurality of assemblies. The voltage applied to each of the plurality of center electrodes is detected by respective voltage sensors, and a differentiated value is calculated by differentiating the applied voltage, detected by each voltage sensor, with respect to time. A judgment is made as to whether or not a differentiated value change state in which an absolute value of the differentiated value becomes equal to or greater than a predetermined threshold value occurs. A judgment is made as to whether or not the occurrence of the differentiated value change state is caused by the noise, according to the voltage applied, for a specific time from the occurrence of the differentiated value change state, to the center electrode where the differentiated value change state has occurred.

A plurality of assemblies are prepared, and a predetermined voltage is applied to a center electrode of each of the plurality of assemblies. The voltage applied to each of the plurality of center electrodes is detected by respective voltage sensors, and a differentiated value is calculated by differentiating the applied voltage, detected by each voltage sensor, with respect to time. A judgment is made as to whether or not a differentiated value change state in which an absolute value of the differentiated value becomes equal to or greater than a predetermined threshold value occurs. A judgment is made as to whether or not the occurrence of the differentiated value change state is caused by the noise, according to the voltage applied, for a specific time from the occurrence of the differentiated value change state, to the center electrode where the differentiated value change state has occurred.

A method for monitoring an ignition system including a spark plug of an internal combustion engine is disclosed. The method comprises determining an operation value associated with an electrical parameter indicative of an operation of the ignition system during actuation of the spark plug. The method further comprises determining at least one parameter indicative of a current engine operation condition of the internal combustion engine, and determining a current spark plug state of the spark plug based on the at least one engine parameter and the operation value associated with the electrical parameter of the ignition system.

A method for monitoring an ignition system including a spark plug of an internal combustion engine is disclosed. The method comprises determining an operation value associated with an electrical parameter indicative of an operation of the ignition system during actuation of the spark plug. The method further comprises determining at least one parameter indicative of a current engine operation condition of the internal combustion engine, and determining a current spark plug state of the spark plug based on the at least one engine parameter and the operation value associated with the electrical parameter of the ignition system.