基于射流点火和气道喷水技术的缸内直喷汽油机稀薄燃烧特性研究  

Study on Lean Combustion Characteristics of Gasoline Direct Injection Engines with Jet Ignition and Intake Water Injection Technologies

作　　者：李勇 吴威龙 李钰怀 陈泓 张宗澜 杜家坤 LI Yong;WU Weilong;LI Yuhuai;CHEN Hong;ZHANG Zonglan;Du Jiakun(GAC Automotive Research&Development Center,Guangzhou 511434,China)

机构地区：[1]广州汽车集团股份有限公司汽车工程研究院,广州511434

出　　处：《内燃机工程》2024年第2期8-17,共10页Chinese Internal Combustion Engine Engineering

摘　　要：在一台4缸涡轮增压汽油机的基础上,增加预燃室和进气道喷水系统,在最佳油耗工况附近(转速2500 r/min,平均有效压力为0.8~1.2 MPa)开展了试验,研究和分析了汽油机稀薄燃烧特性,以及射流点火和进气道喷水技术对稀薄燃烧性能的影响。结果表明,稀薄燃烧可以将有效热效率从当量燃烧的39.5%提高到42.4%左右,但是当过量空气系数超过1.4以后,燃烧稳定性和碳氢排放变差。采用射流点火技术可以将稳定燃烧的过量空气系数拓展到1.7以上,热效率增加至43.0%以上,燃烧持续期最大缩短37.6%,循环波动不超过1.3%。在此基础上增加进气道喷水,对于平均有效压力在1.1 MPa以上的负荷,抑制爆震效果明显,喷水脉宽达到4 ms时,爆震限制的燃烧重心可以提前到活塞上止点后8°左右,同时最大热效率超过44%,循环波动不超过3%;但是对于平均有效压力低于1.1 MPa的负荷,爆震现象不严重,喷水反而会降低燃烧速率和热效率,同时燃烧稳定性和未燃碳氢排放也随之恶化。Based on a four-cylinder turbocharged gasoline engine,a pre-chamber and an intake water injection system were added.Experimental tests were conducted at the optimal fuel consumption conditions(2500 r/min,brake mean effective pressure(BMEP)=0.8~1.2 MPa)to analyze the characteristics of the lean combustion of a gasoline engine,as well as the effects of jet ignition and intake water injection on lean combustion performance.The results show that lean combustion can increase the brake thermal efficiency(BTE)from 39.5%for stoichiometric combustion to around 42.5%.However,combustion stability and total hydrocarbon(THC)emissions deteriorate when the excess air ratio exceeds 1.4.By adopting jet ignition technology,the excess air ratio for stable combustion can be extended to above 1.7,and the BTE can increase to over 43%.The combustion duration can be reduced by a maximum of 37.6%,and the cycle of variation(COV)does not exceed 1.3%.Furthermore,with the addition of intake water injection,the knocking suppression effect is significant for loads with BMEP above 1.1 MPa.When the water injection pulse width reaches 4 ms,the knock-limited CA50 can be advanced to approximately 8°after top dead center,while achieving a maximum BTE of over 44%and COV within 3%.However,for loads with BMEP below 1.1 MPa,since knocking is not serious,water injection instead reduces the combustion rate and thermal efficiency,while worsening combustion stability and THC emissions.

关 键 词：汽油机 稀薄燃烧 预燃室 射流点火 喷水 

分 类 号：TK417[动力工程及工程热物理—动力机械及工程]