缸内残余废气系数对汽油机性能的影响及测试方法研究  

Effects of residual gas on gasoline engine performance and research on test method for residual gas

作　　者：赵智超 王书千 刘敬平 付建勤[2,3] 关尽欢 刘琦[2,3] ZHAO Zhichao;WANG Shuqian;LIU Jingping;FU Jianqin;GUAN Jinhuan;LIU Qi(China Automotive Engineering Research Institute Co.Ltd.,Chongqing 401122,China;Research Center for Advanced Powertrain Technology,Hunan University,Changsha 410082,China;State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body,Hunan University,Changsha 410082,China)

机构地区：[1]中国汽车工程研究院股份有限公司,重庆401122 [2]湖南大学先进动力总成技术研究中心,湖南长沙410082 [3]湖南大学汽车车身先进设计制造国家重点试验室,湖南长沙410082

出　　处：《中南大学学报（自然科学版）》2018年第11期2723-2730,共8页Journal of Central South University:Science and Technology

基　　金：国家重点研发规划专项(2017YFB0103503);中国科协青年人才托举工程项目(2017QNRC001)~~

摘　　要：为研究缸内残余废气对汽油机性能及排放的影响,在1台单缸机上进行排气再循环(exhaust gas recirculation,EGR)扫描试验。为降低残余废气系数、测试成本并简化计算流程,提出1种两稳态传感器测量方法并推导简化数模。采用2个稳态压力传感器测取进气和排气压力,与气门开闭时刻、转速、预存的气门升程、气道流量系数联立求解得到残余废气系数。在1台先进乘用车汽油机上进行试验验证。研究结果表明:残余废气的热容及充量稀释作用降低了燃烧温度,减缓了燃烧速率,使10%～90%燃烧持续期和点火至50%燃烧位置点持续期明显延长;残余废气加热效应促进燃油雾化混合,热容作用降低了燃烧温度从而减少了散热损失,因此,高压循环指示热效率先略微增加,随后由于燃烧燃烧性能下降而迅速降低;残余废气可有效抑制NOX生成,但废气过多会导致HC和CO排放增加;本方法具有较高的预测精度,与三动态传感器方法相比,此方法可大大降低传感器成本,具有工程应用价值。The sweeping test of EGR(exhaust gas recirculation)rate was conducted in a single cylinder engine to research the effects of residual gas fraction(RGF)on engine performance and emission.In order to reduce the cost of RGF measurement and simplify mathematical model,a method by two steady-state sensors was introduced and simplified mathematical model was deduced.Two steady-state pressure sensors were adopted for the measurement of intake and exhaust pressure which was used to solve RGF based on the measured valve timing,engine speed,valve lift and flow coefficient.The test method was verified experimentally on an advanced gasoline engine of passenger car.The results show that the combined effects of thermal capacity and dilution of residual gas decrease combustion temperature and velocity,which obviously prolongs the 10%-90%combustion duration and the period from spark timing to 50%combustion location.The heating effect of residual gas promotes the fuel atomization and the effect of thermal capacity lowers combustion temperature and decreases heat loss,which slightly increases indicated thermal efficiency in high-pressure cycle.With the increase of RGF,the indicated thermal efficiency in high-pressure cycle decreases rapidly due to combustion deterioration.Moreover,residual gas reduces NOX emission but too much residual gas increases HC and CO emissions.The test method has good precision and can lower the cost greatly for engineering application compared with the method by three dynamic pressure sensors.

关 键 词：汽油机 残余废气系数 燃烧 排放 

分 类 号：U467.21[机械工程—车辆工程] U467.22[交通运输工程—载运工具运用工程]