A system includes a cylinder, a piston, a sensor configured to detect vibrations of the cylinder, piston, or both that correspond with varying pressures within the cylinder, and a controller coupled to the sensor. The controller is configured to receive a first signal from the sensor corresponding with first vibrations of the cylinder and to deduce from the first signal a first operating value of a parameter indicative of peak firing pressure at a first time, to compare the first operating value with a baseline value of the parameter indicative of peak firing pressure to detect a change in peak firing pressure, to receive a second signal from the sensor corresponding with second vibrations of the cylinder and to deduce from the second signal a second operating value of the parameter indicative of peak firing pressure at a second time, and to compare the second operating value with the baseline value to confirm the change in peak firing pressure.

In one embodiment, a method is provided. The method includes receiving a signal representative of an engine vibration transmitted via a knock sensor, wherein the knock sensor is disposed in an engine. The method additionally includes deriving a valve wear measurement during operation of the engine based on the signal. The method further includes communicating the valve wear measure.

A method for extracting characterizing features from an ion current trace retrieved from spark plugs of cylinders of an internal combustion engine, comprises the steps of: i. dividing the ion current signal into crank angle subintervals; 5 ii. calculating a measure of ion current in each crank angle subinterval; and iii. Performing a calculation on the measure of ion currents from different subintervals such that the result of the calculation is dimension free. Further it relates to a method of monitoring combustion processes where a plurality of ion current signals from a number of spark plugs (4A, 4B) are 10 retrieved and used in combination.

Provided is an engine knocking detection apparatus capable of reasonably implementing necessary measures for water and dust proofing and against breaking of a cable, and the like at low cost as well as precisely detecting and effectively suppressing or avoiding knocking while suppressing cost and weight increases as much as possible. The engine knocking detection apparatus is adapted to detect knocking in an engine that adopts a flywheel magneto ignition system with an ignition coil unit securely attached to a cylinder, the ignition coil unit including an iron core, a coil wound around the iron core, and a control circuit board attached to the coil, and has an accelerometer for knocking detection attached to the iron core of the ignition coil unit.

Systems and methods for estimating an engine event location are disclosed herein. In one embodiment, a control system is configured to receive feedback from at least one knock sensor coupled to a reciprocating engine, estimate an engine parameter based at least on the feedback and an Empirical Transform Function (ETF), estimate a location of an engine event based on the engine parameter, and adjust operation of the reciprocating engine based at least on the location of the engine event.

A method and a device for knock control of an internal combustion engine, a knock signal of a cylinder of the internal combustion engine being measured by a knock sensor and, on the basis thereof, a knock intensity is generated. The knock intensity is compared to a reference level in order to classify a combustion as a knocking or non-knocking combustion. Moreover, an arrangement is provided, which takes the level of the knock intensity into account for the determination of the reference level.

A method for extracting characterizing features from an ion current trace retrieved from spark plugs of cylinders of an internal combustion engine, comprises the steps of: i. dividing the ion current signal into crank angle subintervals; ii. calculating a measure of ion current in each crank angle subinterval; and iii. Performing a calculation on the measure of ion currents from different subintervals such that the result of the calculation is dimension free. Further it relates to a method of monitoring combustion processes where a plurality of ion current signals from a number of spark plugs (4A, 4B) are retrieved and used in combination.

Methods and systems are provided for mitigating knock and/or pre-ignition. Each of a spark timing retard, cylinder enrichment, and engine load limiting is adjusted based on a knock sensor output generated in a single defined crank angle window, and not based on knock sensor output generated outside the defined crank angle window. A severity of the mitigating actions is adjusted in proportion to the knock sensor output intensity with the severity of the mitigating action increased as the knock sensor output intensity increases.

Methods and systems are provided for diagnosing a knock sensor of an engine system by actively inducing knock in an engine cylinder. A laser ignition device is operated in an engine cylinder located closest to the knock sensor while the engine is at rest and with the cylinder parked with an intake valve and an exhaust valve closed to generate and trap heat in the cylinder. Spark timing is advanced in the cylinder on the subsequent restart, which in combination with the trapped heat induces knock, and elicits a response from a functional knock sensor.

A method for detecting the anti-knocking capacity of a fuel in an internal combustion engine, which comprises the step of analyzing the single combustion cycles of the cylinders to be repeated until a counter reaches a respective threshold value; the step of calculating the mean spark advance operated by the internal combustion engine in the single combustion cycles of the cylinders that have allowed said counter to reach the respective threshold value; and the step of determining the anti-knocking capacity of the fuel as a function of the first counter that has reached the respective threshold value and as a function of the mean spark advance operated by the internal combustion engine in the single combustion cycles of the cylinders that have allowed said counter to reach the respective threshold value.