Abstract: A method is provided for determining an index representing the crank angle at which a given fuel mass fraction has been burnt in a cylinder of the engine during an engine cycle. The method includes, but is not limited to sampling the pressure within the cylinder during the engine cycle, using the pressure samples for determining the heat release rate curve during the engine cycle, using the heat release rate curve for determining the cumulative heat release curve during the engine cycle, determining a minimum value and a maximum value of the cumulative heat release curve, using the given fuel mass fraction for calculating a target value of the cumulative heat release between the minimum and maximum values, finding a goal point of the cumulative heat release curve that corresponds to the target value, assuming the crank angle corresponding to the goal point as the index.

Abstract: A method for operating an internal combustion engine includes measuring pressure values in a combustion chamber during an engine cycle and a corresponding value of crankshaft angular position for each pressure value and selecting values from the pressure values and the corresponding value of crankshaft angular position for each selected value. The corresponding values of the crankshaft angular position are used to calculate a corresponding inner volume value of the combustion chamber for each of the selected pressure values. For each of the selected pressure values and the corresponding inner volume value, a polytrophic constant is calculated according to C=pVk, C being the polytrophic constant, p the pressure value, V the inner volume value, and k the polytrophic index. A root mean square deviation (RMSD) of the polytrophic constant values is calculated and that a noise has affected the pressure values is identified if the RMSDs exceed a threshold value thereof.

Abstract: A pressure monitoring system for a combustion engine includes, but is not limited to of combustion chambers and pressure sensors associated to at least some of the combustion chambers. A multiplexer has inputs connected to at least a first one and a second one of the pressure sensors. A non-zero phase shift exists between the operating cycles of first and second ones of the combustion chambers associated to the first and second pressure sensors. A controller controls the multiplexer to output data from the first pressure sensor while the first combustion chamber is in a predetermined portion of its operating cycle and pressure data from the second pressure sensor while the second combustion chamber is in the predetermined portion of its operating cycle.

Abstract: An embodiment of the invention provides a method for determining the pressure offset of an in-cylinder pressure sensor of an internal combustion engine, comprising the steps of: setting a plurality of couples of instants during an engine cycle within the cylinder; acquiring the pressure measured by the in-cylinder pressure sensor in each instant of each couple of instants; calculating a plurality of pressure offset values, each of which as a function of the pressures measured in a correspondent couple of instants (?iA, ?iB); setting an admissible pressure offset range; selecting the pressure offset values that fall within the admissible pressure offset range; and, if the number of selected pressure offset values is greater than a minimum allowable limit, calculating a final pressure offset as a function of the selected pressure offset values.

Abstract: A method is provided for determining an index representing the crank angle at which a given fuel mass fraction has been burnt in a cylinder of the engine during an engine cycle. The method includes, but is not limited to sampling the pressure within the cylinder during the engine cycle, using the pressure samples for determining the heat release rate curve during the engine cycle, using the heat release rate curve for determining the cumulative heat release curve during the engine cycle, determining a minimum value and a maximum value of thee cumulative heat release curve, using the given fuel mass fraction for calculating a target value of the cumulative heat release between the minimum and maximum values, finding a goal point of the cumulative heat release curve that corresponds to the target value, assuming the crank angle corresponding to the goal point as the index.

Abstract: A pressure monitoring system for a combustion engine includes, but is not limited to of combustion chambers and pressure sensors associated to at least some of the combustion chambers. A multiplexer has inputs connected to at least a first one and a second one of the pressure sensors. A non-zero phase shift exists between the operating cycles of first and second ones of the combustion chambers associated to the first and second pressure sensors. A controller controls the multiplexer to output data from the first pressure sensor while the first combustion chamber is in a predetermined portion of its operating cycle and pressure data from the second pressure sensor while the second combustion chamber is in the predetermined portion of its operating cycle.