Method for detecting knocking combustion in the operation of an internal combustion engine
AssigneesDaimlerChrysler AG, Temic Telefunken microelectronic GmbH
InventorsPeter Hohner, Klaus Knolmayer, Joerg Miroll, Linhard Niemetz
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Abstract
In a method for detecting knocking combustion during the operation of an internal combustion engine with a device for measuring the ionic current, the raw ionic current signal or the evaluated value of the knocking intensity are normalized. This enables the value of the knocking intensity to be reliably compared with a threshold value. The normalization avoids the falsifying influence of large intensity fluctuations of the raw ionic current signal from one combustion cycle to the next without any relation to the true knocking intensity.
Claims30
Method for detecting knocking combustion during operation of an internal combustion engine, in which a raw ionic current signal (IS(t)) is measured by an ionic current probe during a combustion stroke in combustion chambers of the internal combustion engine, from which a value of a knocking intensity (KI) is evaluated, wherein fluctuations in an intensity of the raw ionic current signal (IS(t)) are compensated for by performing a normalization of the raw ionic current signal (IS(t)) or the value of the knocking intensity (KI), wherein the chronological form of the raw ionic current signal (IS(t)) is composed first of ignition faults, then of a first maximum of the combustion, and then of a second maximum of the raw ionic current signal, and wherein an ionic current amplitude value (IM), that is the maximum value of the second maximum of the raw ionic current signal (IS(t)), or an ionic current integral value (II), that is the value of an integration of the raw ionic current signal (IS(t)), is currently determined for performing the normalization after each combustion stroke.
A method of detecting knocking combustion in an internal combustion engine having at least one combustion chamber operating in a succession of combustion cycles, comprising the following steps carried out for a respective present combustion cycle of said succession of said combustion cycles:
- a) sensing an ionic current in said combustion chamber during a combustion stroke of said present combustion cycle, and providing a raw ionic current signal corresponding to said ionic current, wherein said raw ionic current signal has a chronological form comprising a first signal portion corresponding to ignition faults during said combustion stroke, a second signal portion corresponding to a first maximum of combustion during said combustion stroke, and a third signal portion corresponding to a second maximum of said ionic current, and wherein said raw ionic current signal of said present combustion cycle exhibits an intensity fluctuation relative to respective previous raw ionic current signals of previous combustion cycles of said succession of said combustion cycles;
- and
- b) carrying out one of:
- a step b1) of evaluating said raw ionic current signal to determine therefrom a value of a knocking intensity and then normalizing said value of said knocking intensity to provide a normalized value of said knocking intensity, or
- a step b2) of normalizing said raw ionic current signal to provide a normalized ionic current signal and then evaluating said normalized ionic current signal to determine therefrom a normalized value of a knocking intensity;
- wherein said normalizing includes substeps of determining a normalization factor and using said normalization factor to normalize said raw ionic current signal or said value of said knocking intensity for said present combustion cycle, and
- wherein said normalization factor is an ionic current amplitude value that corresponds to a maximum value of said second maximum in said raw ionic current signal of said present combustion cycle, or said normalization factor is an ionic current integral value that corresponds to a value of an integration of said raw ionic current signal of said present combustion cycle.
Dependencies are inferred from the claim text.