Control unit of internal combustion engine

A control unit of an internal combustion engine comprising:

• a knocking sensor detecting a vibration waveform of an internal combustion engine;
• a crank angle sensor detecting a crank angle of said internal combustion engine;
• specified frequency extracting means extracting a vibration level of a specified frequency from a vibration waveform of said internal combustion engine;
• peak signal extracting means extracting a first peak value, being the maximum value of the vibration level of said specified frequency in a predetermined crank angle range, and a crank angle at which said first peak value takes place;
• noise level storage means in which stored is a vibration level of a noise to take place on said specified frequency due to operation of an electric or mechanical operating member that is provided in said internal combustion engine;
• noise occurrence timing estimation means estimating a crank angle at which a noise peak value, being a peak value of said noise vibration, takes place, based on an operation timing of said operating member;
• noise removing means calculating a second peak value based on said first peak value in the case that a crank angle at which said first peak value takes place and a crank angle at which said noise peak value is estimated to take place are not in coincidence, and calculating the second peak value based on said first peak value and said noise peak value in the case that a crank angle at which said first peak value takes place and a crank angle at which said noise peak value is estimated to take place are identical;
• BGL calculation means calculating a background level (BGL), being the average of said second peak value;
• threshold calculation means calculating a threshold for knocking determination based on said second peak value and said background level;
• knocking determination means determining the presence or absence of the occurrence of a knocking based on said second peak value and said threshold for knocking determination;
• knocking strength calculation means calculating a knocking strength based on said second peak value, said threshold for knocking determination and said background level when the occurrence of a knocking is determined by said knocking determination means;
• retard amount calculation means calculating a knocking retard amount of an ignition timing based on a knocking strength having been calculated by said knocking strength calculation means;
• and
• ignition timing correction means correcting an ignition timing based on the knocking retard amount having been calculated by said retard amount calculation means.