Kasprzyk Piotr, Hunicz Jacek, Rybak Arkadiusz, Gęca Michał S, Mikulski Maciej
Faculty of Mechanical Engineering, Lublin University of Technology, 20-618 Lublin, Poland.
School of Technology and Innovations, Energy Technology, University of Vaasa, 65200 Vaasa, Finland.
Sensors (Basel). 2020 Nov 23;20(22):6701. doi: 10.3390/s20226701.
The paper investigates the operation of a wideband universal exhaust gas oxygen (UEGO) sensor in a diesel engine under elevated exhaust backpressure. Although UEGO sensors provide the excess air ratio feedback signal primarily in spark ignition engines, they are also used in diesel engines to facilitate low-emission combustion. The excess air signal is used as an input for the fuel mass observer, as well as to run the engine in the low-emission regime and enable smokeless acceleration. To ensure a short response time and individual cylinder control, the UEGO sensor can be installed upstream of a turbocharger; however, this means that the exhaust gas pressure affects the measured oxygen concentration. Therefore, this study determines the sensor's sensitivity to the exhaust pressure under typical conditions for lean burn low-emission diesel engines. Identification experiments are carried out on a supercharged single-cylinder diesel engine with an exhaust system mimicking the operation of the turbocharger. The apparent excess air measured with the UEGO sensor is compared to that obtained in a detailed exhaust gas analysis. The comparison of reference and apparent signals shows that the pressure compensation correlations used in gasoline engines do not provide the correct values for diesel engine conditions. Therefore, based on the data analysis, a new empirical formula is proposed, for which the suitability for lean burn diesel engines is verified.
本文研究了宽带通用废气氧（UEGO）传感器在柴油机排气背压升高情况下的运行情况。尽管UEGO传感器主要在火花点火发动机中提供过量空气比反馈信号，但它们也用于柴油机以促进低排放燃烧。过量空气信号用作燃油质量观测器的输入，以及用于使发动机在低排放工况下运行并实现无烟加速。为确保较短的响应时间和单缸控制，UEGO传感器可安装在涡轮增压器上游；然而，这意味着排气压力会影响所测量的氧浓度。因此，本研究确定了在稀薄燃烧低排放柴油机的典型工况下该传感器对排气压力的敏感度。在一台配备模拟涡轮增压器运行的排气系统的增压单缸柴油机上进行了识别实验。将用UEGO传感器测得表观过量空气与在详细废气分析中获得的过量空气进行比较。参考信号与表观信号的比较表明，汽油发动机中使用的压力补偿相关性对于柴油机工况无法提供正确值。因此，基于数据分析，提出了一个新的经验公式，并验证了其对稀薄燃烧柴油机的适用性。
