Abstract
Engine knock limits the thermal efficiency improvement of spark-ignition (SI) engines. Thus, the extract research of the knock characteristics has a great significance for the development of gasoline engines. The research proposes a novel knock detection and diagnosis method in SI engines using the CEIITD (Complementary Ensemble Improved Intrinsic time-scale decomposition) and Bi-spectrum algorithm. The CEIITD algorithm is used to extract the knock characteristics. The results show that the CEIITD algorithm can effectively and clearly extract the knock shock characteristics (including light knock) through the vibration signals. A Bi-spectrum analysis can further distinguish between the light knock signal and normal combustion signal. The Bi-spectrum results also show that knock characteristic has a strong non-Gaussian property. At last, the Band pass filter and Improved ITD method were employed to identify the knock characteristics from these cylinder block vibration signals. The comparison result shows that the CEIITD method proposed in this paper is more suitable to detect the knock characteristic.
Highlights
Nowadays, the small strengthening technology (Downsizing) represented by gasoline direct injection pressure and turbocharging is an important technical way to improve the thermal efficiency of gasoline engines, but, with the enhancement of the small strengthening technology, the occurrence probability of engine knock increased significantly [1]
Since the Bi-spectrum can suppress the Gaussian distribution in the signal completely, the distribution and intensity information of the non-Gaussian component in the dual frequency domain is revealed
A new knock feature detection method is proposed for spark ignition engines based on the Complement Ensemble Improved Intrinsic Time-scale Decomposition (CEIITD) and Bi-spectrum
Summary
The small strengthening technology (Downsizing) represented by gasoline direct injection pressure and turbocharging is an important technical way to improve the thermal efficiency of gasoline engines, but, with the enhancement of the small strengthening technology, the occurrence probability of engine knock increased significantly [1]. On the other hand, the light knock is nearly constant volume combustion, in favor of the engine thermal efficiency and improved fuel economy, and is the ideal working condition. These methods can measure the combustion parameters inside the combustion chamber, which can be influenced by knock. These methods can identify engine knock more accurately. The indirect method is used for assessing the knock intensity by measuring vibration signals of cylinder block. Due to durability and low cost, the vibration signal analysis has become the most widely used method to determine the engine knock
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