瞬变工况下多缸汽油机各缸进气均匀性

Uniformity of Individual Cylinder Intake Gas in a Multi-Cylinder Gasoline Engine Under Transient Conditions

采用动态压力实测与数值计算相耦合的方法,在路试工况下对一台搭载在乘用车上的多缸汽油机各缸进排气参数进行连续检测,得到随循环数变化的各缸气体状态变化历程.通过对比分析各缸进、排气参数(如缸内新鲜充量、残余废气量等)差异性的变化范围及影响因素,揭示了各缸残余废气系数不均匀性的变化规律和诱因,以及对进气性能的影响.结果表明,在中低转速和负荷区域,各缸残余废气系数相对偏差在±10%,以内,此时主要受进气平均压力的影响;在高速高负荷区域,各缸残余废气系数相对偏差在±20%,以内,此时主要受排气压力波的影响.优化发动机排气系统结构和布置方式,是改变各缸进气均匀性的重要途径.

By using the coupling method of dynamic pressure measurement and numerical calculation,the intakeand exhaust parameters of individual cylinder of a mutipile-cylinder vehicle gasoline engine were continuouslydetected in road tests,and the gas conditions changing with cycle number were obtained.Through the comparativeanalysis of the changing range and influencing factors of intake and exhaust parameters,such as fresh charge andresidual gas,the change law and incentive of the inhomogeneity of residual gas fraction(RGF)of individual cylinderand their influences on the intake performance were obtained.The results show that under low-medium speedand load operations,the relative deviation of RGF in individual cylinder is within±10%,and mainly affected bymean intake pressure;under high speed and load conditions,the maximum relative deviation is within±20%,and mainly affected by exhaust pressure wave.As a result,optimizing the structure and arrangement of engineexhaust systems is an important way to improve the homogeneity of intake gas in individual cylinder.