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.

中文翻译：

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具有排气背压补偿的柴油机xcess空气比管理

本文研究了柴油机中宽带通用废气氧气（UEGO）传感器在较高的废气背压下的运行情况。尽管UEGO传感器主要在火花点火发动机中提供过量空气比率反馈信号，但它们也用于柴油发动机中以促进低排放燃烧。多余的空气信号用作燃料质量观测器的输入，以及在低排放状态下运行发动机并实现无烟加速。为了确保较短的响应时间和独立的气缸控制，UEGO传感器可以安装在涡轮增压器的上游；但是，这意味着废气压力会影响测得的氧气浓度。因此，这项研究确定了稀燃低排放柴油机在典型条件下传感器对排气压力的敏感性。鉴定实验是在增压单缸柴油机上进行的，排气系统模拟了涡轮增压器的运行。用UEGO传感器测得的表观过量空气与详细废气分析中获得的空气进行了比较。参考信号和视在信号的比较表明，汽油发动机中使用的压力补偿相关性未提供柴油发动机工况的正确值。因此，在数据分析的基础上，提出了新的经验公式，验证了其对稀燃柴油机的适用性。用UEGO传感器测得的表观过量空气与详细废气分析中获得的空气进行了比较。参考信号和视在信号的比较表明，汽油发动机中使用的压力补偿相关性未提供柴油发动机工况的正确值。因此，在数据分析的基础上，提出了新的经验公式，验证了其对稀燃柴油机的适用性。用UEGO传感器测得的表观过量空气与详细的废气分析中获得的空气相比较。参考信号和视在信号的比较表明，汽油发动机中使用的压力补偿相关性未提供柴油发动机工况的正确值。因此，在数据分析的基础上，提出了新的经验公式，验证了其对稀燃柴油机的适用性。