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对V型12缸柴油机缸盖振动燃烧段信号与缸内压力进行了时域对比,分析了失火时的缸盖振动响应,研究了供油规律随转速变化情况。分析表明缸盖振动中包含喷油器针阀落座的振动响应,研究了基于短时能量动态双阈值端点检测提取针阀落座响应时间特征的方法,利用振动信号的峰值加速度来表征针阀落座的强度。在不同工况及不同状态下提取了针阀落座时间及强度的振动特征,结果表明:振动特征能够有效反映针阀的工作情况,可以用于燃油喷射系统故障的诊断。
The time domain comparison of signal and cylinder pressure of V-type 12-cylinder diesel engine cylinder head was carried out. The vibration response of cylinder head during misfire was analyzed, and the variation of fuel supply law with rotational speed was studied. The analysis shows that the vibration of the cylinder head covers the vibration of the needle seat of the injector. The method of extracting the characteristic of the seating response time of the needle valve based on the dynamic double-threshold endpoint detection of the short-time energy is studied. The peak acceleration of the vibration signal is used to characterize the valve seating strength. The vibration characteristics of the seated time and strength of the needle valve were extracted under different working conditions and different conditions. The results show that the vibration characteristics can effectively reflect the working condition of the needle valve and can be used to diagnose the fault of the fuel injection system.