基于S变换的柴油机燃烧差异的诊断研究

Study on Diagnosis of Diesel Engine Combustion Difference Based on S-transform

分析了传统的基于平稳过程的傅里叶变换存在的局限性,采用了S变换时频分析法对振动信号进行分析。对比不同燃烧状况时的缸内压力曲线、压升率曲线及振动信号S变换的结果,表明振动信号S变换得到的时频图像同缸内燃烧过程有密切的关系。为了便于对各缸的燃烧状况进行定量分析,提出了利用时频域内各点的幅值和表征各缸燃烧差异的新方法。在4缸柴油机上进行模拟试验对该方法进行验证,结果验证了该方法的有效性。

The limitation of Fourier transform conventionally based on stationary process was analyzed, and then the vibration signal was analyzed with S-transform time-frequency method. Comparing pressure inside cylinder, pressure rise rate and the vibration signal transformed results with S-transform during different combustion conditions, it was found that the vibration signal time-frequency image with S-transform had close relations with combustion process inside cylinder. For the quantitative analysis of combustion difference in different cylinders, the new method that the combustion difference in different cylinders were indicated with the amplitude of different points in time-frequency domain was put forward. The method is verified in a 4- cylinder diesel engine by simulation test and the result indicates the method is feasible.