新型两阶段点火系统对稀燃效率的影响

摘要

基于自行开发的两阶段点火系统,采用准纳秒级伏安特性测试和发动机试验,研究了系统的放电特性、各阶段能量分配规律和在稀燃工况下的表现.结果表明:该系统放电过程主要由击穿阶段、高功率阶段和辉光阶段构成;高功率阶段可在持续时间约为20μs内释放150 ～ 550 mJ能量,约占整体释放能量的80％ ～ 90％,且受到气压变化的影响较小;击穿阶段持续时间约为10 ns,能量占比小于1％,击穿能量随气压升高而增加;发动机对比测试显示两阶段点火可以使稀燃边界从过量空气系数φa=1.36提升至φa=1.70;结合稀薄燃烧,与普通点火相比相对热效率可提升最高10％.%Based on an innovative two-stage ignition system,the discharge characteristics,the energy distribution and lean bum performance were studied by using the quasi-nanosecond volt-ampere test and engine test.Results show that the discharge process of this system is mainly composed of breakdown stage,high power stage and glow stage.The high power stage can deliver 150-550 mJ energy within about 20 μs,which contributes about 80％-90％ energy proportion and little change with the pressure variation.The breakdown stage lasts about 10 ns,which takes an energy proportion of less than 1％ and increases with higher pressure.Engine test results show that the twostage ignition system can improve the lean limit from φa =1.36 to φa =1.70.Moreover,combined with lean burn,it can achieve up to 10％ relative thermal efficiency improvement compared with normal ignition system.