三火花塞点火系统对混动专用发动机稀燃性能影响试验研究

An Experimental Study on the Effect of Triple Spark Plug Ignition System on the Lean Combustion Performance of Dedicated Hybrid Engine

基于一台三缸1.5TGDI增压直喷发动机研究了三火花塞点火均质稀燃对发动机性能的影响。结果表明:三火花塞可有效拓展稀燃极限,压缩比15时,采用三火花塞在2000 r/min、8 bar BMEP的特征工况点可实现lambda 1.95的稳定燃烧,最低油耗相比单火花塞降低约5 g/(k W·h),NO_(x)原始排放可降低至约50×10^(-6),此时lambda受增压能力限制难以进一步增加;压缩比增加至16所能实现的最低油耗相比压缩比15改善不明显,且稀燃极限有所下降。三火花塞对爆震倾向改善作用较小,但可显著加快稀混合气的燃烧速率,相同lambda条件下其燃烧持续期相比单火花塞可缩短约3-6℃A,lambda 1.95时的燃烧持续期相比当量燃烧仅增加约2℃A。通过对潜在最高热效率的研究表明,采用三火花塞设计可在压缩比15条件下最终实现45.02%的有效热效率。

A study is conducted on a three-cylinder 1.5TGDI turbocharged direct injection engine,in terms of the effect of triple spark plug(TSP)ignition on the lean combustion performance.The results show that TSP can effectively extend the lean burn limit,with compression ratio of 15,the TSP can achieve stable combustion at lambda 1.95 for the specific operating condition of 2000 r/min 8 bar BMEP,with the minimum brake specific fuel consumption(BSFC)reduced by 5 g(/kW·h)compared with that of the single spark plug,and raw NOx emission reduced to about 50×10^(-6).At this condition,the limit for a further lambda increase is mainly due to the boost capability.When the compression ration increases to 16,the minimum BSFC improvement is not obvious compared with that of the compression ratio of 15,and the lean burn limit decreases.The TSP has little benefit for reducing the knock tendency,but can increase the lean mixture combustion rate obviously,at the same lambda condition,its combustion duration can be 3-6℃A shortened compared to single spark plug,and increase by only 2℃A at lambda 1.95 compared to stoichiometric combustion.Through a further investigation on the potential maximum thermal efficiency,it shows that with the compression ratio of 15,the TSP can finally achieve 45.02% maximum brake thermal efficiency.