声强直接测定法在发动机故障诊断中的应用

Direct Method for Sound Intensity Acquisition Applied in Engine Fault Diagnosis

提出了一种基于虚拟仪器技术的声强直接测定方法。根据双传声器声强测试原理,将声强传感器采集的信号交由数据采集系统完成A/D转换,经过数字滤波,计算出实时声强(时域声强),取其时间平均得到有功声强(频域声强)。根据该方法测得的发动机时域声强信号提取二次矩、四次矩以及时间二次矩,提高了发动机不同工况的特征区分度,从而提高了故障诊断的准确性和有效性。通过声强标定仪的校准,以及对发动机声强的实际测量和诊断试验,证明该方法是准确有效的。

Based on virtual instruments, the direct method of sound intensity acquisition was discussed. According to the principle of sound intensity test with double microphones, signals captured by sound intensity sensor were transformed in a data acquisition system. Then the real time sound intensity （time domain sound intensity） signals via digital filter were obtained. Finally, the active sound intensity （frequency domain sound intensity） signals was obtained by time average. Based on the method, the engine time domain sound intensity signals were converted to diagnostic index, the difference of characteristics among different working conditions of engine were enhanced, and the accuracy and validity of fault diagnosis were improved. Through sound intensity calibrator testing, the engine sound intensity measurement and diagnostic examination, the method proved correct and reliable. The new method of sound intensity acquisition, developed in this work, provides a new way for the inspection of engine working condition and fault diagnosis.