Knock signal analysis for gasoline engines based on discrete wavelet transform
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摘要: 为提高爆震检测精度,研究了离散小波变换在爆震信号分析中的应用.利用离散小波变换从汽油机的振动信号中提取出了轻微爆震特征,提出了一种根据离散小波变换特征域子带信号能量大小来评价爆震强度的指标,根据爆震发生时特征域子带信号能量阶跃变化的特性,提出了确定爆震阈值的方法,该方法经检验能准确判断发生爆震的临界值.研究成果为将小波变换应用于汽油机爆震的实时精确控制打下基础,可进一步通过点火提前控制使汽油机在轻微爆震区工作,汽油机的动力性、经济性都能够得到提高.Abstract: For the increasing of knock detection precision, the application of discrete wavelet transform(DWT) in the analysis of gasoline engine knock signal was studied. First, the knock feature was extracted from gasoline engine cylinder block acceleration signals by using DWT. Then, the parameter for evaluating knock intensity based on the energy of DWT decomposition detail coefficient was put forward. According to the character of DWT decomposition detail coefficient energy step change when knock took place, the method of confirming the knock threshold value was brought out, and the effectiveness of the method was also tested. The research results build the foundation of applying DWT to accurate and real-time knock control of gasoline engine. Further more, gasoline engine can work at slight knock zone by spark advance control, and the performance of gasoline engine can also be improved.
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Key words:
- gasoline engine /
- knock /
- wavelet transform
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