Method for recognizing at least one feature of the fuel in an internal combustion engine
A method recognizes at least one feature of fuel in an internal-combustion engine ( 1 ). The method comprises steps of: detecting, by at least one sensor, intensity (S) of vibrations generated by the internal-combustion engine ( 1 ) within a measurement-time window; determining a value of at least one synthetic index (I) by processing the intensity (S) of the vibrations generated by the internal-combustion engine ( 1 ) within the measurement-time window; comparing a synthetic index (I) with at least one predetermined comparison quantity (TH); and recognizing the feature of the fuel as a function of the comparison between the synthetic index (I) and comparison quantity (TH).
1. A method for recognizing at least one feature of fuel in an internal-combustion engine ( 1 ), said method comprising steps of:
detecting, by at least one sensor, intensity (S) of vibrations generated by the internal-combustion engine ( 1 ) within a measurement-time window;
determining a value of at least one synthetic index (I) by processing the intensity (S) of the vibrations generated by the internal-combustion engine ( 1 ) within the measurement-time window;
comparing a synthetic index (I) with at least one predetermined comparison quantity (TH); and
recognizing the feature of the fuel as a function of the comparison between the synthetic index (I) and comparison quantity (TH).
2. A recognition method according to claim 1 , wherein said step of recognizing the feature of the fuel comprises further steps of:
assigning a first value to the feature of the fuel if the synthetic index (I) is higher than the comparison quantity (TH); and
assigning a second value different than the first value to the feature of the fuel if the synthetic index (I) is lower than the comparison quantity (TH).
3. A recognition method according to claim 1 , wherein said step of recognizing the feature of the fuel comprises a further step of calculating the value of the feature of the fuel by an interpolation performed as a function of the comparison between the synthetic index (I) and comparison quantity (TH).
4. A recognition method according to claim 1 , wherein said step of determining the value of the synthetic index (I) comprises further steps of:
calculating FFT of the intensity (S) of the vibrations generated by the internal-combustion engine ( 1 ) within the measurement-time window; and
calculating the value of the synthetic index (I) as a function of an amplitude of at least one harmonic of the FFT.
5. A recognition method according to claim 4 , wherein the value of the synthetic index (I) is a function of the amplitude of a second harmonic of the FFT.
6. A recognition method according to claim 4 , wherein the value of the synthetic index (I) is a function of a sum of the respective amplitudes of at least two even harmonics of the FFT.
7. A recognition method according to claim 6 , wherein the value of the synthetic index (I) is a function of the sum of the respective amplitudes of a second harmonic of the FTT and a fourth harmonic of the FFT.
8. A recognition method according to claim 4 , wherein the value of the synthetic index (I) is a function of a ratio between the amplitude of an even harmonic of the FFT and the amplitude of an odd harmonic of the FFT.
9. A recognition method according to claim 4 , wherein the value of the synthetic index (I) is a function of a ratio between a sum of the respective amplitudes of at least two even harmonics of the FFT and a sum of the respective amplitudes of at least two odd harmonics of the FFT.
10. A recognition method according to claim 4 , wherein the synthetic index is correlated with a feature of peak of the amplitude of the harmonic of the FFT.
11. A recognition method according to claim 1 , wherein the synthetic index (I) is directly determined as a function of a variation in time of the intensity (S) of the vibrations generated by the internal-combustion engine ( 1 ) and correlated with timbre of the intensity (S) of the vibrations.
12. A recognition method according to claim 1 , wherein said method comprises further steps of:
associating the comparison quantity (TH) to a given recognition-operating point of the internal-combustion engine ( 1 ); and
performing the comparison between the synthetic index (I) and comparison quantity (TH) when a current operating point of the internal-combustion engine is in a neighborhood of the recognition-operating point.
13. A recognition method according to claim 1 , wherein the feature of the fuel is the percentage of ethanol present in the fuel.
14. A recognition method according to claim 1 , wherein the sensor is a microphone ( 6 ) that detects the intensity (S) of noise generated by the internal-combustion engine ( 1 ).
15. A recognition method according to claim 1 , wherein the sensor is an accelerometer ( 7 ) that detects the intensity (S) of mechanical vibrations generated by the internal-combustion engine ( 1 ).