废气再循环温度对小排量增压汽油机燃烧及性能的影响

Effect of EGR Temperature on Combustion and Performance in Small Displacement Turbocharged Gasoline Engine

为研究不同废气再循环(EGR)温度对汽油机燃烧特性的影响,基于一台1.3T涡轮增压汽油机改造了低压EGR系统,通过开关EGR冷却水使EGR达到不同的温度.结果表明:在1 500r·min-1,10%EGR率,小、中、大3个负荷工况下,随着EGR温度升高,燃油消耗率有升高趋势,但是其升高幅度不超过0.3%.EGR温度升高后,最佳点火提前角提前,中、小负荷燃烧持续期增长,大负荷燃烧持续期基本不变.在大负荷工况下,当关闭EGR冷却后,EGR温度急剧升高,会对进气过程产生不利影响,发动机最大仅能达到的平均有效制动压力为1.166 MPa,相比于该转速下10%EGR率低温EGR能达到的1.202 MPa,下降了3%.

In order to study the effect of different EGR temperatures on combustion characteristics of gasoline engine,a low pressure EGR system was set up on a 1.3 L turbocharged gasoline engine.Different EGR temperatures were controlled by switching EGR cooling water.The results show that with the increase of EGR temperature,the fuel consumption rate was increased but lower than 0.3% at 1 500 rpm and a 10% EGR rate operating point.With the increase of EGR temperature,MBT(minimum advance for best torque) was advanced,combustion duration was extended under low and medium load conditions,but basically unchanged under high load condition.Under high load condition,EGR temperature was increased sharply without EGR cooling water,the intake process was negatively affected,and BMEP could only reach 1.166 MPa.Compared with low temperature EGR in which BMEP can reach1.202 MPa,there is a decreased by 3%.