摘要
为了深入分析连续可变气门升程(CVVL)系统对增压直喷(TGDI)汽油发动机性能的影响,通过对典型工况点的台架测试,对比分析了可变气门升程对HC、NOx、CO、比油耗以及平均指示有效压力燃烧循环变动系数(COV-IMEP)的影响规律.结果表明,在各个转速下,COV-IMEP随发动机负荷增加而下降;低转速中等负荷时,COV-IMEP随气门升程的减小显著下降.HC随气门升程下降而下降,但下降幅度较小.NOx随气门升程下降显著上升,通过优化气门升程和推迟排气门正时机构相位角,可以有效抑制NOx的上升.利用CVVL系统的上述特点,在综合工况循环冷起动排放优化中,更多推迟点火角,加速三效催化器的起燃,而COV-IMEP保持在可接受的水平,从而大幅降低了排放水平.
In order to deeply analyze the influence of continuously variable valve lift(CVVL)system on the performance of turbo-charged gasoline direct injection engine(TGDI),through the bench test of typical working conditions,the effect law of variable valve lift on HC,NOx,CO emissions,brake specific fuel consumption(BSFC)and the coefficient of cycle variation of indicated mean effective pressure(COV-IMEP)is comparatively analyzed.The results show that the COV-IMEP decreases with the increase of engine load at various speeds,while the COV-IMEP decreases significantly with the decrease of valve lift at low speeds and medium loads.HC decreases with the decrease of valve lift,but the decrease is small while NOx increases with the decrease of valve lift significantly,but the increase of NOx can be effectively suppressed by optimizing valve lift and delaying the phase angle of exhaust variable valve timing(VVT).For cold start emission optimization in new European driving cycle(NEDC),the ignition angles are delayed more and the light-off of three-way catalysts is accelerated by using the above characteristics of CVVL system,so that the emission level is greatly reduced while COV-IMEP remains acceptable level.
作者
韩本忠
李理光
张力华
HAN Benzhong;LI Liguang;ZHANG Lihua(School of Automotive Studies,Tongji University,Shanghai 201804,China;United Automotive Electronic Systems Co.,Ltd.,Shanghai 201206,China)
出处
《同济大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2019年第S01期32-38,共7页
Journal of Tongji University:Natural Science
关键词
连续可变气门升程(CVVL)系统
燃烧循环变动
排放
燃烧持续期
驾驶循环
continuously variable valve lift system(CVVL)
coefficient of variation
emissions
combustion duration
new European driving cycle(NEDC)
