基于排气噪声的柴油机失火故障诊断

通过计算机和声传感器采集排气噪声，研究九种工况下柴油机排气噪声的频谱规律。通过对柴油机排气噪声信号功率谱分析，提取二个参数来表征排气噪声的频谱规律。对这两个参数在各工况下的值进行了详细的分析后，发现这两个参数在失火工况下有较大的变化，故对这两个参数确定相应的阈值来诊断失火故障。通过编写相应的故障诊断程序，输入排气噪声样本和对应的转速后即可判断出失火故障。这种方法具有非接触，操作简单，成本低的特点。

Fault Diagnosis of Misfire in Diesel Engines Based on Exhaust Noise

In this paper, exhaust noise signal is collected by computer and microphone. The frequency spectrum law of the exhaust noise in nine operating modes is investigated. Two parameters are picked-up through power spectrum analysis of the exhaust noise. Detailed analysis of dependent of these parameters on each operating mode is carried out. It is found that these parameters have great changes under the misfire operating mode. Hence, the threshold values corresponding to these parameters are determined to diagnose the misfire operating mode. The corresponding fault diagnostic program is written. The misfire fault can be identified quickly after inputting the sample of exhaust noise and the corresponding rotational speed. This method has the characteristics of non-contact, easy to operate, and low costs.