变采样率变采样阶比发动机在线监测系统研究

Online Monitoring System of Engine for Variable Sampling Rate and Sampling Order

针对车用发动机在线监测与故障诊断中各传感器信号频率成分相差较大、需要同步采样及信号非平稳的情况,分析了阶比跟踪技术在发动机各类信号处理方面的优势。通过软件实现了各通道信号同步变采样率采集。通过抗混叠滤波器截止频率及发动机最低转速计算出了各通道所需的最低采样阶比,避免了繁琐的阶比跟踪滤波对原信号带来的误差和干扰。对正常及故障工况下变速时的排气噪声、缸盖振动及外卡油压信号进行变采样率变采样阶比的阶比跟踪后,用于在线监测及故障诊断的信号特征更加明显,且更利于通过程序自动提取。

For the different frequency component, synchronized sampling demand and non-stationary characteristics of sensor signals in the online monitoring and fault diagnosis system for vehicle engine, the advantages of order tracking technology were analyzed in the signal processing of different signals. The synchronized sampling of diverse sampling rate for different signals was achieved by the software. The best sampling order for each channel was computed by the cut-off frequency of anti-aliasing filter and the lowest speed of engine, which avoided the error and interference from the complicated order filter. The diverse sampling rate and sampling order tracking of exhaust noise, cylinder head vibration and gripper piezo-electricity signal were car- ried out, and hence the signal characteristics applied in the online monitoring and fault diagnosis were strengthened and easier to be acquired by the program.