A method is provided for detecting autoignition in a spark-ignited internal combustion engine, wherein values for the combustion chamber pressure are measured during a compression stroke of the internal combustion engine at defined crankshaft angles within an evaluation window, a filtered pressure value is determined from the measured values for the combustion chamber pressure, and theoretical pressure values in the combustion chamber that would arise if no combustion took place in the combustion chamber are determined for the defined crankshaft angles. The value of the slope between two defined crankshaft angles for filtered pressure values is determined, the value of the slope between two defined crankshaft angles for theoretical pressure values is determined, and a difference of the slope values is calculated therefrom. This difference is compared with a specified threshold value, and, if the threshold value is exceeded, an autoignition in the combustion chamber is inferred.

A method for processing a voltage signal relating to the pressure prevailing in a combustion chamber of a cylinder of an internal combustion engine, the signal, referred to as an input signal, having, in alternation, plateau phases and main peak phases. The method includes a step (E1) of rectification of the input signal such that the gradient of the base signal is zero, a step (E2) in which the peaks of the rectified signal of which the amplitude is greater than a predetermined voltage value are clipped so as to obtain an at least partially clipped signal referred to as a clipped signal, a step (E3) of detection of a main peak when the amplitude of the input signal is greater than the amplitude of the clipped signal, and a step (E4_1, E4_2) of compensation of the input signal in the absence of such a detection.

An engine control unit includes an extracting portion acquiring a sound or vibration of an engine from external and extracting vibration components of frequency bands each of which including a resonant frequency of a vibration mode, a waveform synthesis portion synthesizing the vibration components extracted by the extracting portion to generate a synthesis vibration waveform, a calculation portion calculating a time average value by averaging the synthesis vibration waveform in a predetermined time, a peak detection portion detecting a peak strength of the vibration component of the frequency band including a lowest resonant frequency, a storage portion previously storing a first threshold and a second threshold, and a determination portion determining an existence of a knocking and whether a knock level is a first knock level or a second knock level, by comparing the time average value with the first threshold and comparing the peak strength with the second threshold.

A method for processing a signal of a pressure measuring device inside an internal combustion engine, the device including: a pressure measuring sensor supplying an output voltage signal (S.sub.B), and a processing unit connected to the pressure measuring sensor, the method including the following steps: I. calculating a duration (Dt1) between a first time (t0) corresponding to a first combustion pressure peak (P0) and a second time (t1) corresponding to a second combustion pressure peak (P1), consecutive to the first combustion pressure peak (P0), II. calculating a correction start time (t.sub.c1) defined according to the previously calculated duration (Dt1), III. measuring a value of the signal (V.sub.OFF1) at the correction start time (t.sub.c1), IV. correcting the signal, on the basis of the correction start time (t.sub.c1) in relation to a reference value (V.sub.REF) and obtaining a first processed signal (S) such that:
S=S.sub.BV.sub.OFF1+V.sub.REF.

A knocking determination device detects a vibration generated in an internal combustion engine during a predetermined period in each combustion cycle of the internal combustion engine. The knocking determination device performs a knocking determination of a presence or absence of a knock based on a vibration waveform in a predetermined frequency band component of the vibration detected.

Disclosed is a method of processing a periodic voltage signal, called the input signal, relating to the pressure existing in a combustion chamber of a cylinder of an internal combustion engine. The method includes a step (E6) of determining a second instant of unlocking of the base signal during a second peak phase, a step (E7) of determining a second instant of locking, which is subsequent to the second instant of unlocking and for which the input signal is in the plateau phase consecutive to the second peak phase, and a step (E8) of generating a base signal between the second instant of unlocking and the second instant of locking on the basis of a slope value of a straight line determined during a first peak phase between a first instant of unlocking and a first instant of locking.

In one embodiment, a system includes an engine control system configured to control an engine. The engine control system comprises a processor configured to receive a vibration signal sensed by a knock sensor disposed in an engine. The processor is further configured to correlate the vibration signal with a fingerprint having at least an ADSR envelope indicative of the operating event of a valve train of the combustion engine, analyze the vibration signal with a statistical valve train model, or a combination thereof. The processor is also configured to detect if the operating event has occurred based on correlating of the noise signal with the fingerprint, based on analyzing the vibration signal with a statistical valve train model, or a combination thereof, and to control the valve train based on the operating event.

A method or system to determine peak firing pressure of a cylinder of an engine having a crank shaft. The method includes accessing a knock signal received from a knock sensor of the cylinder. The method includes determining a location of peak firing pressure based at least in part on the knock signal. The location of peak firing pressure is associated with combustion of the engine and corresponds to a time or a crank angle of the crankshaft. The method includes generating an indication of the location of peak firing pressure.

The present invention relates to a method for controlling the performance of an engine, comprising the steps detecting an ion current in the form of a first signal analysing said first signal to determine at least one property determining a knock index based on said first signal and preferably on said at least one property combining said knock index with a plurality of factors related to properties of the engine or the operation of the engine to arrive at a engine index, and comparing said engine index with a sensitivity map of the engine to determine a correction required to improve the operation of the engine, and correcting the operation of the engine in accordance with the correction determined. The invention also relates to a system for controlling the performance of an engine.

Disclosed is a method of processing a periodic voltage signal, called the input signal, relating to the pressure existing in a combustion chamber of a cylinder of an internal combustion engine. The method includes a step (E6) of determining a second instant of unlocking of the base signal during a second peak phase, a step (E7) of determining a second instant of locking, which is subsequent to the second instant of unlocking and for which the input signal is in the plateau phase consecutive to the second peak phase, and a step (E8) of generating a base signal between the second instant of unlocking and the second instant of locking on the basis of a slope value of a straight line determined during a first peak phase between a first instant of unlocking and a first instant of locking.