燃烧室EGR策略下汽油CAI燃烧试验Ⅰ:气门定时影响及实现CAI燃烧定时区域

Experimental on Gasoline CAI Combustion with Combustion Chamber EGR Strategy Ⅰ:Effects of valve timing and valve timing zone of CAI combustion

燃烧室EGR策略是实现可控自燃(CAI)的一种有效技术手段.在装备电控液压驱动可变气门机构的单缸机试验系统上,研究了使用燃烧室EGR策略实现CAI燃烧时,进、排气门定时对汽油CAI燃烧的影响.试验结果表明,在1,000,r/min采用对称负气门重叠角(NVO)定时变化时,在NVO为140～240°CA内能够实现CAI燃烧,采用非对称的NVO定时变化,可以拓宽实现CAI燃烧的NVO范围,改善CAI燃烧状态.此外,排气门关闭定时对缸内残余废气量的影响要大于进气门开启定时,在能实现CAI燃烧的气门定时区域内,排气门关闭角(EVC)变化范围较小为50°CA,进气门开启角(IVO)变化范围可达200°CA.

Combustion chamber EGR strategy is an effective technical approach to achieve the controlled auto ignition.The effects of valve timing on gasoline CAI combustion was investigated using the combus-tion chamber EGR strategy and single-cylinder testing system equipped with a new electro-hydraulic vari-able valve-train system.Experimental results show that,with symmetrical intake valve opening time and exhaust valve closing time,CAI combustion achieved at 1,000,r/min when NVO durations are between 140°CA and 240°CA.While the non-symmetrical NVO strategy can broaden NVO scope and improve the CAI combustion.Results also show that the influence of exhaust valve closing timing on residual gas is larger than that of intake valve opening timing.In CAI combustion region,variation in exhaust valve clos-ing timing is 50°CA and variation in intake valve opening timing is 200°CA.