DEVICE FOR DETECTING KNOCKING IN INTERNAL COMBUSTION ENGINE

摘要

PURPOSE:To improve an S/N ratio by using a filter which passes only the frequency band of the knocking and a filter for measuring only back-ground noises, and separating the knocking signal and the noises at an early stage. CONSTITUTION:The output signal from a knocking detector 2 which is mounted on a cylinder block of an engine 1 is introduced to a knocking detecting device 3. Ignition times are controlled so as to obtain the optimum positions based on the output of the device. The output of the knocking detector 2 is divided into two systems in the knocking detecting device 3. One outputs is amplified through the filter 311 which passes only the frequency band of the knocking. The other is integrated in an integrator 33 through the filter 312 which passes only the frequency band other than the knocking and an amplifier 322, and compared with the knocking signal from the filter 311 in a comparator 34, as to whether the knocking is present or absent. Based on the comparared result, a control signal is sent to an ignition time control circuit 4 from a judging circuit 35.