柴油机气阀漏气故障声发射诊断特征参数

Parameter for Valve Leakage Diagnosing Fault for Diesel Engines Based on Acoustic Emission

气阀漏气是气缸盖声发射信号源之一,但缸盖声发射信号特征与柴油机的类型和气缸盖结构等密切相关,这影响到声发射特征参数的通用性.根据柴油机的结构及配气相位,分析了柴油机气阀漏气与其激励的声发射信号的关系,在某小型柴油机台架上试验研究了缸盖声发射信号的提取方法,根据气动声学公式,提出了基于漏气激励声发射频段能量法的气阀漏气特征参数,并在其他不同两类柴油机上进行了试验验证,结果表明:该方法具有很好的通用性,可为不同机型柴油机气阀漏气诊断提供技术参考.

Valve leakage is one of the acoustic emission （AE）exciting sources of cylinder head, and the characteristic of AE is closely related to the type of diesel engines and structure of cylinder heads, bringing its difficulty to the applicability of the leakage diagnostic method. Based on the structure and valve timing of a diesel engine, the relationship between valve leakage and AE generated by the leakage was analyzed in this paper. The feature extraction method of cylinder head AE was experimentally studied on a small diesel engine. Based on the aeroacoustics equations and AE band energy, a diagnostic parameter of valve leakage was proposed and verified by experiments from two diesel engines. It has shown that the proposed diagnostic parameter has good universality and can be used as a reference for diagnosing various types of diesel engines.