Method And Device For Detecting Auto-Ignitions On The Basis Of Measured And Estimated Internal Cylinder Pressure Values Of An Internal Combustion Engine

A device for detecting auto-ignition in a combustion chamber of a spark-ignited internal combustion engine, the device configured to:

• during a compression stroke of the internal combustion engine, acquire values for a combustion chamber pressure in the combustion chamber at defined crankshaft angles within an evaluation window,
• determine a filtered pressure value from the acquired values for the combustion chamber pressure,
• determine, for the defined crankshaft angles, theoretical pressure values in the combustion chamber that would occur if no combustion were to take place in the combustion chamber,
• determine a value of the pressure difference between the filtered pressure value and the theoretical pressure values,
• compare the value of the pressure difference with a predefined threshold value, and
• determine an auto-ignition in the combustion chamber upon a determination that the threshold value is exceeded.

A spark-ignited internal combustion engine comprising:

• at least one cylinder which, together with a piston connected to a crankshaft, bounds a combustion chamber, a combustion chamber pressure sensor configured to measure a pressure in the combustion chamber,
• a crankshaft angle sensor that supplies a signal which represents the crankshaft angle,
• a control device configured to perform open-loop and/or closed-loop control of the internal combustion engine, and
• a device for detecting auto-ignition in the combustion chamber by:
• during a compression stroke of the internal combustion engine, acquiring values for a combustion chamber pressure in the combustion chamber at defined crankshaft angles within an evaluation window,
• determining a filtered pressure value from the acquired values for the combustion chamber pressure,
• determining, for the defined crankshaft angles, theoretical pressure values in the combustion chamber that would occur if no combustion were to take place in the combustion chamber,
• determining a value of the pressure difference between the filtered pressure value and the theoretical pressure values,
• comparing the value of the pressure difference with a predefined threshold value, and
• determining an auto-ignition in the combustion chamber upon a determination that the threshold value is exceeded.