汽油机均质稀燃点火系统的试验研究

Experimental Study on Ignition System of Homogeneous Lean Burn Gasoline Engine

稀薄燃烧技术是当前先进的提升汽油发动机热效率的关键技术之一。当前稀燃技术应用的难点之一是为稀燃混合气提供高的点火能量。这是因为当缸内的混合气被稀释,着火的时间被延长,而且火焰的传播速度慢,会导致完全燃烧变得更加困难。故急需要匹配高能点火系统,解决稀燃混合气着火困难的问题。为了解决均质超稀薄混合气点火的困难,对3种不同类型的高能点火系统进行了研究,介绍了普通高能点火系统、长放电持续期高能点火系统和电晕点火系统的原理和工作模式。然后在同一台基础发动机上进行稀燃性能摸底试验,控制试验的边界条件相同,选择相同的工况点进行过量空气系数的扫点,对比不同高能点火系统测试结果,重点分析不同高能点火系统对发动机油耗、燃烧和排放的影响。通过所测高能点火的试验结果分析可以得出,电晕点火这种体积点火方式的高能点火系统能够有效点燃准фat> 1.8超稀燃混合气,能有效地拓宽稀薄燃烧极限,对稀燃技术有很好的提升。

Lean burn technology is one of the key technologies for improving the thermal efficiency of gasoline engines. One of the difficulties in the current application of lean-burn technology is to provide high ignition energy for the lean-burn mixture. The leaning of the mixture, the delay in ignition, coupled with the slow flame propagation, makes complete combustion more difficult. Therefore, it is urgent to match the high-energy ignition system to solve the problem of difficulty in catching the lean-burn mixture.In order to solve the problem of difficult ignition of lean-burning gas mixture, this paper has carried out basic research on different high-energy ignition systems, and introduced the system principle and working mode of ordinary high-energy ignition system, long-discharge duration high-energy ignition system and corona ignition system. Then, the lean-burning performance test is carried out on the same basic engine. During the bench test, we controlled the conditions the same. The same operating point is selected to sweep the excess air coefficient. Then we compared the test results of different high energy ignition systems, mainly focused on the effects on fuel consumption, combustion and emissions. It could be concluded from the test results that the volume-ignited high-energy ignition system of corona ignition can effectively ignite the lean mixture of λ >1.8, which can effectively expand the lean-burn limit. The tested corona ignition system can bring benefit to lean burn technology.