Combustion noise detection in an internal combustion engine

摘要

The claimed invention relates to a method for monitoring combustion noise in an internal combustion engine by means of a knock sensor for the purpose of detecting knock or pre-combustion in the engine. Combustion noise at a first cylinder of the engine is monitored using a knock sensor over a sensing window to obtain measured combustion noise intensity. A set of noise parameters including an opening noise duration, an opening delay, a closing noise duration and a closing delay corresponding to an injector event occurring on a second cylinder is then looked up. An estimate of opening noise and an estimate of closing noise falling within the sensing window based on the injection timing at the second cylinder and on the set of noise parameters is computed. Finally a compensated noise intensity is determined by subtracting the estimates of opening and closing noise from the measured combustion noise intensity at the first cylinder. This compensated noise intensity is used to detect the presence of knock or pre-ignition in the first cylinder. In the method of the invention the injector operation noise is compensated for in the measured noise intensity rather than disabling or modifying detection thresholds when an injector event overlaps with the knock sensor detection window as seen in prior art systems. Also disclosed is a method of determining noise in a multi-cylinder combustion engine.