高原变海拔对柴油机缸压信号的影响分析

摘要

For the failure on fire surface of cylinder head for a heavy-duty diesel engine at high altitude,the hypothesis that the increase of impulse frequency led by in-cylinder fluctuation was the failure reason was put forward.Then the in-cylinder pressure signals at different altitudes were collected at a plateau simulation test bed for a single cylinder engine and the ensem-ble empirical mode decomposition(EEMD)was conducted.Different frequency components of in-cylinder signal were extracted and their power spectral densities were carried out in each condition.It was found that the energy of high frequency components increased with the increase of altitude by analyzing energies of extracted different frequency components.Accordingly,the pro-posed hypothesis was feasible.%针对高原变海拔条件下,某重型柴油机缸盖火力面出现麻点这一故障,提出了随着海拔上升,缸内压力波动剧烈,进而导致对缸盖火力面冲击频次剧增的失效原因假设.为此,通过可模拟高原变海拔环境的单缸机台架试验,采集不同海拔下的缸内压力信号,并对其作集平均经验模态分解(Ensemble Empirical Modal Decomposi-tion,EEMD),分离出缸压信号的不同频率成分,并对每个工况下的功率谱密度进行对比分析.结果表明:通过对分离出来的不同频率成分的能量进行分析,发现缸压高频分量的能量随海拔升高而增加,进而验证了缸盖麻点这一失效现象的假设成立.