基于内禀模态高频积分能量法的煤油发动机爆震因子计算方法

提出了基于内禀模态高频积分能量法的爆震因子计算方法.该方法对电控二冲程煤油发动机缸内燃烧压力信号进行经验模态分解，自适应得到若干内禀模态函数分量与残余函数.对内禀模态函数分量采用快速傅里叶变换得到爆震高频信号分量，选取残余函数峰值对应的曲轴转角为爆震窗口起始曲轴转角，对爆震窗口宽度分析，得到合理爆震窗口宽度持续曲轴转角为30°.利用内禀模态高频积分能量法对无爆震、轻微爆震、中度爆震与强烈爆震工作循环的缸内燃烧压力信号进行爆震因子计算，得到4个工作循环的爆震因子分别为0.6642，1.8191，3.0275，5.3717，可表征爆震的强弱.研究表明基于内禀模态高频积分能量法的爆震因子计算方法简便、快速有效. 

Calculating method of knock factors based on method of intrinsic mode function high-frequency integral energy for kerosene engine

The method of intrinsic mode function high-frequency integral energy was proposed. In this method,the cylinder combustion pressure signals of the electronic controlled two-stroke kerosene engine were decomposed into a finite number of intrinsic mode function components and the residual function using the empirical mode decomposition method. The knock high frequency signal component was obtained by analyzing the intrinsic mode function components using the fast Fourier transform(FFT). The crank angle corresponding to the peak of the residual function peak was chosen as the starting crank angle of the knock window. Then the knock factors were calculated using the method of intrinsic mode function high frequency integral energy based on the knock high frequency signal component. By analyzing the knock window width, it's learnt is that a reasonable constant crank angle of knock window width is 30°. Knock factors of cylinder combustion pressure signals for four cycles were calculated using the method of intrinsic mode function high-frequency integral energy. Four cycles include non-knocking cycle, slight knock cycle, moderate knock cycle and strong knock cycle. The knock factors of four cycles include 0.6642, 1.8191, 3.0275 and 5.3717, which could represent the strength of knock. Research shows that the method of intrinsic mode function high-frequency integral energy in the process of knock factors calculation for the electronic controlled two-stroke kerosene engine is practical and effective.