内燃机气阀漏气故障的高阶谱分析

High-order Spectral Analysis of Leakage Faults for Internal Combustion Engine Valve

将高阶谱理论引入内燃机的振动诊断中,分析了不同状态时缸盖表面振动信号的三阶谱特性,并计算出三阶谱的峰值,用于刻划各状态时缸盖系统的非线性行为。结果表明:正常状态时缸盖表面振动信号的三阶谱接近为零,可以认为缸盖系统是线性系统;当气阀发生漏气故障时,缸盖表面振动信号的三阶谱就会出现较大的峰值,而且不同状态时所对应的峰值也存在着较大差别,说明不同气阀漏气状态时缸盖系统表现出不同程度的非线性。可以将三阶谱的峰值作为判断气阀是否漏气的一个诊断特征量,同时也为诊断内燃机气阀的早期漏气故障提供了依据。

The theory of high-order spectrum is applied to the vibration diagnosis of internal combustion engines in this paper. The high-order spectral characteristics of vibration signals from the cylinder head of the exhaust valve in different conditions are analyzed. Its peak value is computed and applied to describe the nonlinear behavior of the cylinder head in different conditions. Results show that the three-order spectrum is close to zero in normal conditions and here cylinder head is regarded as a linear system. The great peak value of three-order spectrum in fault conditions appears and it shows that the cylinder head tends to a nonlinear system. The peak value varies in different fault conditions and it can be used as a characteristic for diagnosing leakage fault of exhaust valve, the fault in initial stages can also be diagnosed.