Patent ID: 8676534

Claim:
Method for determining a rotation speed of at least one supercharger ( 14 ) which compresses a sucked air in an internal combustion engine ( 1 ); the determination method, during a normal operation of the internal combustion engine ( 1 ), comprises the steps of: detecting, by means of a microphone ( 25 ), an intensity of a sound signal generated by the rotation of the supercharger ( 14 ); and; determining an evolution in time of a frequency content of the sound signal generated by the rotation of the supercharger ( 14 ); the determination method is wherein it comprises the further steps of: acquiring, in a preliminary setting-up and design phase, the nominal operation characteristic of the supercharger ( 14 ) which provides the rotation speed of the supercharger according to a compression ratio (β) and to a flow rate (AM Compr ) of air running through the supercharger ( 14 ); determining, completely irrespective of the sound signal generated by the rotation of the supercharger ( 14 ), a first estimation of the rotation speed of the supercharger ( 14 ) according to the compression ratio (β) between an output pressure (P outC ) and an input pressure (P inC ), which is calculated according to an atmospheric pressure value (P atm ) and to the flow rate of the air sucked by the internal combustion engine ( 1 ), according to the flow rate (AM Compr ) of air running through the supercharger ( 14 ), preferably corrected according to an air temperature (T air ), and using the nominal operation characteristic of the supercharger ( 14 ); determining an interval of plausible frequencies of the rotation speed of the supercharger ( 14 ) based on the first estimation of the rotation speed of the supercharger ( 14 ); determining a second estimation of the rotation speed of the supercharger ( 14 ) according to the frequency content of the sound signal generated by the rotation of the supercharger ( 14 ) within the interval of plausible frequencies; and validating the second estimation of the rotation speed of the supercharger ( 14 ) by means of the first estimation of the rotation speed of the supercharger ( 14 ).