在自行搭建的发动机试验台架上,以台架试验与排放分析法为基础,以NI采集卡、前端信号处理电路、信号丢失控制电路与信号异常控制电路等为硬件,以LabVIEW软件为技术支持设计了天然气发动机氧传感器故障模拟系统,分析了天然气发动机氧传感器故障对发动机动力性、经济性以及各项排放指标的影响。试验结果表明:当转速为2 500r.min-1,节气门开度为25%,模拟信号电压低于0.5V时,过量空气系数变小,混合气变浓,转矩与正常值相比变化不大,CO排放上升,HC排放略有升高,但变化不大,NOx排放下降;当模拟信号电压高于0.5V时,过量空气系数变大,混合气变稀,转矩下降较大,CO排放下降,并低于正常值,HC排放上升,NOx排放基本为0。
On the self-built engine test bench, the bench test and emission analysis method were taken as foundations, the NI acquisition card, front-end signal processing circuit, the control circuit of signal loss and the control circuit of signal anomaly were taken as hardwares, the fault simulation system of oxygen sensor for natural gas engine was designed by LabVIEW software, and the influences of oxygen sensor fault on the power performance, economy performance and emission indexes of natural gas engine were analyzed. Test result shows that when rotation speed is 2 500 r ~ min-1 , throttle opening degree is 25% and analog signal voltage is below 0.5 V, the excess air coefficient reduces, the concentration of mixed gas rises, torque changes slightly compared with normal value, CO emission rises, HC emission rises slightly, and NO~ emission decreases. When signal voltage is high above 0.5 V, the excess air coefficient rises, the concentration of mixed gas decreases, torque drops significantly, CO emission decreases and is less than normal value, HC emission increases, and NOx is 0 basically. 2 tabs, 26 figs, 21 refs.