Method for detecting combustion failure by filtering
First Claim
1. A method of detecting misfires of a mixture between a fuel and an oxidizing agent, in any one of the cylinders of an internal combustion engine having multiple-stroke operating cycles, such as two-stroke or four-stroke cycles, this method comprising the following steps:
- a) during at least some of the combustion phases in at least one of the cylinders, at an instant (t) of the engine operating cycles, a current value of an index In(t) representative of operating irregularities in the engine stroke is calculated,b) while the engine is operating, and on the basis of the current value at the instant t of the index In(t), the current value at the same instant t of an observation function G(t) is calculated, this function being a function of an instantaneous discrepancy between said current value at the instant t of the index In(t) and an estimated reference value Ī
n+i(t) illustrative of this index at a different instant,c) the current value of G(t) is compared with a predetermined threshold (S) dependent on the engine load (C) and/or speed (N), andd) a misfire is diagnosed when the value of G(t) crosses the threshold (S), characterized in that;
the observation function G(t) is such that;
G(t)=Ī
n(t)−
In(t),
with Ī
n(t)=Ī
n+i(t)+a×
En(t)Ī
n(t) corresponding to a value representative of the index In(t) after the values of this index that lie outside a predetermined permissible discrepancy (BC) have been excluded and/or weighted and where a is a correction coefficient dependent on |En(t)|,and En(t)=In(t)−
Ī
n+i(t), i being an operating cycle different from n, En(t) being an expression of the instantaneous discrepancy between said current value at the instant t of the index In(t) and the corresponding reference value Ī
n+i(t) illustrative of this index at a different instant.
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Abstract
A method for detecting combustion failure in an internal combustion engine, by calculating an index ln(t) representing engine irregularities at a moment (t) during certain combustion phases in one cylinder; calculating an observation function G(t), which is a function between index ln(t) and an estimated reference value In+/−i(t) at a different moment during engine operation comparing G(t) to a threshold (S), which is a function of engine load (C) and/or rpm (N); and diagnosing a combustion failure when G(t) exceeds (S) or: G(t)=In(t)−ln(t), wherein In(t) is a function of ln(t) and In+/−i(t) represents the index ln(t) after weighting of the values of said index outside an acceptable predefined differential.
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Citations
14 Claims
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1. A method of detecting misfires of a mixture between a fuel and an oxidizing agent, in any one of the cylinders of an internal combustion engine having multiple-stroke operating cycles, such as two-stroke or four-stroke cycles, this method comprising the following steps:
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a) during at least some of the combustion phases in at least one of the cylinders, at an instant (t) of the engine operating cycles, a current value of an index In(t) representative of operating irregularities in the engine stroke is calculated, b) while the engine is operating, and on the basis of the current value at the instant t of the index In(t), the current value at the same instant t of an observation function G(t) is calculated, this function being a function of an instantaneous discrepancy between said current value at the instant t of the index In(t) and an estimated reference value Ī
n+i(t) illustrative of this index at a different instant,c) the current value of G(t) is compared with a predetermined threshold (S) dependent on the engine load (C) and/or speed (N), and d) a misfire is diagnosed when the value of G(t) crosses the threshold (S), characterized in that; the observation function G(t) is such that;
G(t)=Ī
n(t)−
In(t),
with Ī
n(t)=Ī
n+i(t)+a×
En(t)Ī
n(t) corresponding to a value representative of the index In(t) after the values of this index that lie outside a predetermined permissible discrepancy (BC) have been excluded and/or weighted and where a is a correction coefficient dependent on |En(t)|,and En(t)=In(t)−
Ī
n+i(t), i being an operating cycle different from n, En(t) being an expression of the instantaneous discrepancy between said current value at the instant t of the index In(t) and the corresponding reference value Ī
n+i(t) illustrative of this index at a different instant. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification