气门升程对汽油CAI燃烧及气门定时区域影响  

Effects of Valve Lift on Gasoline CAI Combustion and Valve Timing Zone of Engine

作　　者：高锋军[1] 刘发发[1] 谷艳华[1] 谭满志[1] 郭英男[1] 

机构地区：[1]吉林大学汽车动态模拟国家重点实验室,吉林长春130022

出　　处：《内燃机学报》2012年第6期492-498,共7页Transactions of Csice

基　　金：国家重点基础研究发展规划资助项目(2007CB210004)

摘　　要：在改造的4冲程单缸机上,装备自主开发的电控液压驱动全可变气门机构,通过改变进排气门定时和升程截留高温已燃废气实现了汽油均质压燃(CAI)燃烧.通过试验探索了不同升程时的气门定时区域,研究了不同气门升程时,进排气门定时对燃烧的影响.结果表明:在1,000 r/min,采用对称负气门重叠角(NVO)策略,NVO大于180℃A时,发动机实现了正常CAI燃烧;随着气门升程降低,可实现CAI燃烧的NVO区间变大,对应的EGR率也呈增大趋势,NOx排放呈减小趋势.采用非对称NVO策略,拓宽了实现CAI燃烧的NVO范围;相同升程,排气门关闭角(EVC)定时对应EGR率的影响均大于进气门开启角(IVO)定时.气门升程低时,CAI稳定燃烧定时范围大,EVC定时对EGR率的影响显著增强;气门升程高时,可实现CAI燃烧的平均有效压力范围大.The controlled auto-ignition （CAI）combustion was achieved through hot burnt gas trapped in the combustion chamber in a modified single-cylinder gasoline engine, equipped with a self-developed electro-hydraulic variable valve-train system. The operation regions at different lifts were investigated experimentally, and the effects of variable valve timing and lift were studied. Experimental results show that, at 1 000 r/min, when NVO angle is larger than 180°CA, CAI combustion is achieved using the symmetrical negative valve overlap （NVO）strategy. With decreasing valve lift, the NVO angle scope of CAI combustion is broadened, and the corresponding EGR rate increases and NOx emission decreases. Unsymmetrical NVO strategy can broaden the NVO scope of CAI combustion, and the effect of exhaust valve closure （EVC） on EGR rate is higher than that of intake valve opening （IVO） at different valve lifts. With decreasing valve lift, the timing range of stable combustion is enlarged, and effect of EVC timing on EGR rate is also significantly enhanced. With increasing valve lift, the range of brake mean effective pressure （BMEP） for the stable combustion is enlarged.

关 键 词：汽油 电控液压驱动可变气门机构 可变气门升程 可变气门定时 

分 类 号：TK401[动力工程及工程热物理—动力机械及工程]