There are provided a control device and an abnormal combustion detecting method for detecting occurrence of abnormal combustion during an expansion stroke of an internal combustion engine. The control device of the present invention receives a detection signal of a vibration sensor for detecting pressure vibration in a combustion chamber, and detects occurrence of knocking based on a knocking-specific frequency component extracted from the detection signal in a knocking determination region within the expansion stroke. In addition, the control device detects the characteristic value, different from the knocking-specific frequency component, of the detection signal in an abnormal combustion determination region which includes the knocking determination region and which expands over the compression stroke before ignition timing and the expansion stroke, and detects self-ignition during the compression stroke before ignition timing and self-ignition during the expansion stroke, based on the characteristic value.

Systems and methods for operating an engine operated by a controller that has a capacity to determine whether or not misfire occurs in the engine are presented. In one example, an operating region of the engine is broken into a plurality of zones and a misfire threshold level is dynamically provided for each of the plurality of zones based on slowly updated zone-level statistical parameters and quickly updated buffer-level parameters. The real-time dynamic misfire thresholds provide a basis for determining misfire within the engine.

A method of monitoring an operating event of a combustion engine includes receiving a noise signal sensed by a knock sensor disposed in or proximate to the combustion engine, correlating the noise signal with a fingerprint having at least an ADSR envelope indicative of the operating event, and detecting if the operating event has occurred based on the correlating of the noise signal with the fingerprint.

A system includes a controller configured to receive noise signals acquired by at least two knock sensors of a plurality of knock sensors coupled to a reciprocating device. Each noise signal represents a noise signature of the reciprocating device detected at a respective knock sensor. The controller is also configured to determine a location of a coincident noise within the reciprocating device based at least on the received noise signals.

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.

A method of distinguishing piston slap from engine knock in a reciprocating device includes obtaining a fundamental frequency of a cylinder, the cylinder having a thrust face and an anti-thrust face, receiving a first signal from a first knock sensor mounted on the cylinder, and identifying piston slap by evaluating whether a first plurality of amplitudes of the first signal at the fundamental frequency and one or more harmonic frequencies of the fundamental frequency exceed a piston slap threshold value.

A control system includes a first and second sensor configured to monitor a first type of operating condition of a first and second cylinder of an engine, respectively, a feedback component configured to monitor a second type of operating condition of the engine, and a controller communicatively coupled with the first and second sensors and feedback component. The controller is configured to receive a first measurement of the first type of operating condition from the first sensor, a second measurement of the first type of operating condition from the second sensor, and a third measurement of the second type of operating condition from the feedback component, to analyze the first and second measurements to detect a change in operating peak firing pressure in the first cylinder and/or in the second cylinder, and to analyze the third measurement to diagnose a cause of the change.

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.

In a method for recognizing knocking of an internal combustion engine, solid-borne sound signals are measured and solid-borne sound features are recovered from the measured sound signals. A peak pressure for a combustion event of the internal combustion engine is estimated from the solid-borne sound features, and the estimated peak pressure is compared with a knock recognition threshold, knocking of the internal combustion engine being recognized when the knock recognition threshold is exceeded by the estimated peak pressure.

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.