Different Methods of Knock Detection and Knock Control

SI engines are exposed to the risk of knocking combustion if the resistance of the fuel against self ignition is too low. Knocking combustion cycles can be detected by means of the vibration signal energy calculated in a predetermined time window. Based on a continuous signal sampling during quasi-steady engine operation an appropriate data processing technique has been developed to identify the engine operation conditions which are suspected to disturb the knock detection. To increase knock detection reliability a new strategy has been developed; characteristic features are: wideband filtering of the structure vibration, window energy calculation of the signal, determination of the standard deviation of the energy values. A knock control simulation code has been written for the standard deviation strategy. Knock control system calibration can be optimized by aid of this program very efficiently.