Knock detector for vehicle IC engine - digitises and filters knock sensor signal using two digital filters with centre frequency shifting depending on resonance frequency components

摘要

The knock detector contains a knock sensor (15) which detects the mechanical vibrations of the engine and/or the internal cylinder press. fluctuations. The knock signal is digitised (104), filtered (17) and the maximum intensities of two characteristic resonance frequency components are compared with associated background levels to determine centre frequency shifts for two digital filter units. A knock detection signal is generated (83) if a knock index (82) derived from the comparison intensities in both filter units exceeds a threshold. ADVANTAGE - Reliable, accurate knock detection is performed using a limited number of frequency components. Optimal for analysis under all operating conditions over a long period.