Process and system for detecting misfiring in internal combustion engines
AssigneeCentro Richerche Fiat Societa' sortile per Azioni
InventorsMario Palazzetti, Cesare Ponti, Luigi Di Leo
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Abstract
Starting from a sequence of values of indicated torque detected for each expected combustion in the engine a cycle signal is generated as a combination of at least two successive values of the said sequence. The peak value of the said cycle signal is then compared with a comparison threshold chosen preferably in proportion of the fuel injection duration into the cylinders. Misfires are identified preferably from the result of a comparison between the said peak value and the said comparison threshold which differs from the result of comparison in the presence of regular operation of the engine.
Claims18
A process for detecting misfires in an internal combustion engine comprising the steps of:
- detecting an indicated torque value for each expected combustion of the engine, and generating a sequence of said indicated torque values corresponding to said expected combustions,
- generating a cycle signal by combining at least two successive values of said sequence of indicated torque values,
- determining a peak value of said cycle signal,
- determining a threshold value corresponding to an expected torque of the engine in the presence of effective combustion, and
- comparing said peak value with said threshold value and evaluating whether said peak value differs from said threshold value so as to identify a misfire of said engine.
A system for detecting misfires in an internal combustion engine, said system including:
- first sensor means for detecting an instantaneous speed and phase of rotation of said engine, passage of engine cylinders through a top dead center position and a duration of fuel injection into the cylinders of the engine,
- processor means for determining from the engine speed signal, for each expected combustion a value of an indicated torque of the engine, thus generating a corresponding sequence of values;
- wherein said processor means generates as a combination of at least two successive values of said sequence, a cycle signal, determines a peak value of said cycle signal, and determines a threshold value corresponding to the expected torque of the engine in the presence of effective combustion;
- and compares said peak value with said threshold value and determines whether said peak value differs from said threshold value so as to indicate a misfire of the engine, and
- display means controlled by said processor means to present the result of said comparisons and determining whether said peak value differs from said threshold value so as to identify a misfire of said engine.
Dependencies are inferred from the claim text.