Improved knock detection by time variant filtered structure-borne sound

In order to detect knock in spark plug engines generally structure–borne sound signals measured by acceleration sensors mounted on the engine housing are used. At test bed engines additional pressure sensors measuring the pressure inside the combustion chamber deliver a reference signal to adjust the parameters of knock detection based on the sound signal. We show by experimental results that the approximation of pressure signals by time variant filtering of structure–borne sound increases the performance of knock detection significantly. These results can be regarded as an upper boundary of what can be achieved by knock detectors with less computational load.