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分析了二冲程均质发动机UHC和CO的来源,介绍了一种能够大幅度降低UHC和CO的方法.试验是在二冲程发动机怠速废气再循环量较大情况下进行的,怠速时,通过在SI二冲程发动机上增加EGR,发现UHC从7800×10-6降低到3000×10-6,CO从3%降低到0.2%,循环变动也减小了.EGR中的活性物质与新鲜充量充分反应改善了预燃过程.由此证明,可以通过增加EGR实现发动机稳定运行,并在当量比和稀燃条件下得到了同样结果.试验表明,UHC和CO主要来自余隙中的残余燃料,说明燃烧温度不是影响UHC和CO的主要因素,决定因素是第一阶段燃烧前缸内发生的预燃反应程度.活性物质的重要性已被试验证实,试验中用氮气和空气代替EGR稀释混合气,发现火花点火在EGR中是可行的,在空气和氮气中却不行.
The origin of UHC and CO of two-stroke homogeneous engine is analyzed, and a method of reducing UHC and CO can be introduced.Experiments are carried out under the condition of large idle-cycle recirculation of two-stroke engine, SI two-stroke engine to increase EGR, found that UHC reduced from 7800 × 10-6 to 3000 × 10-6, CO decreased from 3% to 0.2%, the cycle changes also reduce the active substance in the EGF with sufficient fresh charge The reaction improved the pre-combustion process, thus demonstrating that it is possible to achieve stable engine operation by increasing EGR with the same results at equivalence ratio and lean burn.The experiments show that UHC and CO mainly come from the residual fuel in the clearance, Combustion temperature is not a major factor affecting UHC and CO, the deciding factor is the degree of pre-combustion reaction occurring in the pre-combustion cylinder in stage 1. The importance of actives has been demonstrated experimentally using nitrogen and air instead of EGR to dilute the mixture, Spark ignition was found to be viable in EGR, but not in air and nitrogen.