Abstract
This paper proposes a method of prompt knock detection for combustion diagnose .The resonant vibration of in-cylinder combustion pressure is used, and knock detection is studied in particular with using the wavelet transformation. The results of simulation and experiment indicate that the wavelet transformation can distinguish the change of resonance frequency the instantaneous signal, and it is especially fit for being used to knock detection, the resonance frequency that changes continuously to change along with the crank angle, also, the vibration energy and changing rate changes equally too when knocking occurring. With this method, knock detection becomes possible for an independent combustion.