基于柴油发动机国六排放应用的氮氧化物传感器碳颗粒堵塞问题研究

针对目前国六柴油发动机应用的氮氧化物传感器被碳颗粒堵塞的问题进行了分析与讨论。为验证影响传感器积碳堵塞的内部和外部条件,采用了发动机台架和整车路试试验方法。通过总时长100 h以上的巴黎循环试验,测试分析了市面上两家主流供应商提供的氮氧化物传感器对于积碳堵塞的鲁棒性差异。试验结果表明:供应商1和供应商2氮氧化物传感器的响应时间均有不同程度的增加,但是供应商2的部件响应时间增幅总体较供应商1大了1倍,因此供应商1的部件在抗积碳能力上优于供应商2的部件。同时通过对不同安装位置的积碳结果进行对比,结果表明:锥面安装的传感器响应时间的增幅和增速都远远高于直管安装的传感器,证实了催化氧化器锥面安装确实会对氮氧化物传感器造成不良的影响,从而导致传感器探头更容易被积碳堵塞。

Research on NOx Sensor Soot Blocking Problem Based on CN6 Diesel Engine Application

The problem related to soot blockage of NO_x sensor applied on CN6 diesel engine was analyzed and discussed.To verify the internal and external conditions that affected the soot accumulated on the sensor,the engine bench test and the vehicle road test were carried out.Through the Paris cycle experiment with a total time of more than 100 h,the robustness difference of NO_x sensors provided by two mainstream suppliers in the market for soot blockage was tested.The experimental results show that the response time of NO_x sensors of supplier 1 and supplier 2 increases to varying degrees,but the increase of response time of components of supplier 2 is twice as large as that of supplier 1.Therefore,the NO_x sensor from supplier 1 has a better robustness against soot contamination than NO_x sensor from supplier 2.The effect of different sensor installation position was also tested,and the result shows that the soot accumulated rate and sensor response time increasing rate for the cone-mounted sensor are dramatically large,compared with the pipe-mounted sensor.The test result provides the evidence that mounting the sensor at the entry cone of diesel oxidizer catalytic does have a harmful effect on sensor soot blockage,which leads to a faster blockage on the sensor probe.