基于某1.5 L采用EGR技术的自然吸气发动机，进行EGR系统优化匹配与分析，重点针对EGR系统应用过程中涉及到的EGR取气位置、各缸EGR均匀性、可使用EGR的环境条件进行了仿真分析与试验验证。结合仿真与试验结果，选择EGR催化器前取气，并优化EGR回气位置，使得各缸EGR率偏差大部分控制在±0.5%以内；使用EGR的温度边界建议：0 km海拔下环境温度大于等于5 ℃，海拔升高时使用EGR的环境温度可降低，发动机冷却液温度介于55~110 ℃；使用EGR的海拔边界建议：海拔小于3 km，同时需综合考虑经济性、动力性及电控可实现性对EGR率进行修正。

Based on a 1.5 L naturally aspirated engine using EGR technology, the optimized matching and analysis of EGR system were carried out, focusing on the simulation analysis and experimental verification of EGR gas extraction position, EGR uniformity of each cylinder, and EGR using conditions involved in the application of EGR system. Combined with the simulation and test results, EGR was selected to take gas before catalyst, and the EGR return air position was optimized, so that the deviation of EGR rate of each cylinder was controlled within ±0.5%. The temperature of using EGR was suggested to be not lower than 5 ℃ at the altitude of 0 km, and could drop while the altitude increased and the temperature of engine coolant should be between 55 ℃ and 110 ℃. The altitude proposal of using EGR was that the EGR rate should be corrected at the altitude of lower than 3 km by comprehensively considering the economy, the power performance and the achievability of ECU control.