摘要
针对批产的CA6DF柴油机,设计了一种具有低压缩比和较大口径的直口型燃烧室、具有高涡流比的进气道和能够实现高EGR率的冷EGR系统,还设计了具有上下2层喷孔的超多喷孔油嘴,这种喷油嘴的上下两束喷雾相互交叉在燃烧室空间形成干涉,并采用高压共轨喷油系统替代机械直列式喷油系统,以有利于实现一种新的低温预混合燃烧,从而达到同时大幅度降低NOx和碳烟排放的目的。综合分析大量试验结果表明,该柴油机在从怠速到标定转速各转速(1 430 r/min除外)所对应的外特性全负荷的50%负荷以下实现了较理想的低温预混合燃烧,NOx和碳烟排放下降幅度均在50%以上,很多工况降幅达80%～90%,且燃油消耗率(BSFC)保持基本不变。特别在低负荷工况,由于过量空气系数高,实现了较理想的稀薄均匀混合气的预混合燃烧,因此即使在非常高的EGR率下BSFC还是与原机相当、有的工况还有所下降。
This study proposed a new low-temperature premixed combustion to achieve the simultaneous reduction of NOx and soot e-missions in a volume production diesel engine of CA6DF by reconstructing the key systems.According to this concept,some develop-ments are as follows.A toroidal combustion chamber of a low compression ratio was developed.Inlet ports of high swirl ratio were de-veloped.A cooled EGR system was developed.Especially an ultramultihole（UMH） nozzle was developed.It has two layers of injec-tion holes and a large flow area.Two sprays of the upper and lower layers meet in the space of the combustion chamber.The high pres-sure common rail fuel injection system replaced the traditional in-line fuel injection system.The results showed that the operation ran-ges of this diesel engine to achieve the low-temperature premixed combustion are as follows.The speed is from the idle speed to the ra-ted speed.The load can reach to 50% of the full load of the corresponding speed（except for 1 430 r/min）.The test diesel engine a-chieved the better low-temperature premixed combustion at these operation ranges,and thus NOx and soot emissions are simultaneously reduced by about 50%,even by 80%～90% at most test cases,while kept the BSFC from being significantly deteriorated.Especially the low load due to the high excess air ratio achieved much more homogeneous lean-mixture premixed combustion.Therefore the BSFC with the heavy EGR is comparable to the original level,even slightly reduced at some test cases.
出处
《现代车用动力》
2010年第4期1-6,共6页
Modern Vehicle Power
关键词
超多喷孔喷油嘴
柴油机
低温预混合燃烧
排放控制
UMH nozzle
diesel engine
low-temperature premixed combustion
emission control
