Knock control apparatus for an internal combustion engine

A knock control apparatus for an internal combustion engine comprising:

• a knock sensor that detects a vibration of the internal combustion engine;
• a crank angle sensor that detects a crank angle of said internal combustion engine;
• a vibration waveform detection unit that detects a vibration waveform of a knock natural frequency component from a detection signal of said knock sensor by making it into association with said crank angle;
• a vibration waveform average value calculation unit that calculates a vibration waveform average value corresponding to a noise vibration waveform generated in a regular manner by carrying out filtering processing of said vibration waveform over a plurality of ignition cycles of said internal combustion engine;
• a noise vibration waveform removal unit that removes said noise vibration waveform by subtracting said vibration waveform average value from said vibration waveform;
• a knock determination threshold value calculation unit that calculates a knock determination threshold value based on a peak value of the vibration waveform after said noise vibration waveform has been removed;
• and
• a knock determination unit that determines whether a knock has occurred in said internal combustion engine, by making a comparison between said peak value and said knock determination threshold value.