高能点火对汽油机性能的影响

本文介绍了492QA2汽油机装用BJHEI 高能点火系统进行的性能试验,研究高能点火对汽油机怠速、超怠速排放及动力性、经济性的影响。     

采用高能点火的均质稀薄燃烧汽油机试验

均质稀薄燃烧能够有效提高汽油机热效率,而高能点火可以提高汽油机的燃烧速度,是实现均质稀薄燃烧的有效技术途径.通过一台单缸汽油机分别研究了普通火花点火和高能点火对均质稀薄燃烧过程的影响,分析了两者燃油经济性、燃烧特性以及NOx排放特性的差异,结果表明:相比于普通火花点火,高能点火能够有效拓宽汽油机均质稀薄燃烧的空燃比极限;采用高能点火系统A可以实现过量空气系数φa为1.65的均质稀薄燃烧,指示燃油消耗率(ISFC)最低达到184.0 g/(kW·h);采用点火能量更高的高能点火系统B可以实现φa为1.94的均质超稀薄燃烧,指示燃油消耗率最低达到180.7 g/(kW·h),对应的指示热效率为48.2%;将φa进一步提升至2.00时,NO_x原始排放将降至188×10~(-6),但受限于燃烧过程恶化,此时ISFC将增加至185.3 g/(kW·h).     

点火能量对通用小型汽油机排放性能影响的研究

针对通用小型汽油机在中小负荷时HC和CO的排放量较高的问题,分析了HC和CO产生的机理.提出了提高点火能量的措施,改善了通用小型汽油机点火可靠性和燃烧过程,试验表明,高能点火能有效降低HC和CO的排放量.     

高能点火系统在CG125发动机上的应用研究

点火能量是影响发动机性能的重要因素,通过提高点火能量可达到降低油耗和改善排放的目的。为此,本文介绍了一种汽油机用高能点火测试系统,并在CG125发动机上进行了高能点火的试验研究。结果表明,使用高能点火后不仅降低了油耗,还在一定程度上提高了发动机的输出功率。     

稀薄燃烧结合高能点火对高压缩比汽油机小负荷工况燃油经济性的影响

汽油机小负荷工况由于泵气损失较大,燃油经济性较差.针对这一问题,基于一台压缩比16的直喷汽油机,结合自主研制的高能点火系统将稀燃极限从1.5拓宽到1.65,最大相对热效率提升22％,其中稀薄燃烧贡献了17％,高能点火贡献了5％.一维数值模拟结果表明,稀薄燃烧可以提高比热比,降低泵气损失和传热损失,高能点火的作用在于加快...     

汽油机点火系统

汽油机点火系统的功能是按汽油机的不同工况,在规定时刻准确可靠地点燃汽油机燃烧室内被压缩的可燃混合气,并且要有足够的点火能量,以满足燃油-空气混合气能充分燃烧的需要。为保证汽油机的动力性和经济性、满足汽油机不同工况(负荷及转速的变化)的要求,点火系统还应能自动调整点火时刻(点火正时)。     

小型汽油机数字点火系统的研究与改进

本文阐述了摩托车数字点火系统的性能对发动机工作过程的影响。介绍了常见的几种数字点火系统。针对常用的数字点火系统C．D．I．进行了改进，设计出一套高能点火系统。通过点火能量试验验证，改进的高能点火系统有效的提高了各个转速的点火能量。     

汽油机瞬态工况点火系统的优化控制

应用微机技术,使汽油机在非爆震区根据发动机的转速和功率由开环控制系统自动寻找点火角度;而在爆震区,则由闭环控制系统对其跟踪调整,至微爆状态。这样,发动机在稳态和瞬态运行都能实现点火系统的最佳控制。本文介绍的正是这种技术在480型汽油机上应用的成果。     

汽油机点火波形及转速遥测器的研制

以ＡＴ８９Ｃ２０５１单片机为核心的汽油机点火波形及转速测示器，运用了无线电收信原理，将汽油机打火瞬间所产生的高频电磁波作为接收信号，经滤波、放大及整形处理后，实现汽油机点火波形的显示与转速的测示     

汽油机点火系故障单片机检测诊断系统

介绍一种利用单片机检测、诊断汽油机点火系故障的分析系统，主要特点是通过检测点火初级线圈在充电、放电时的电流波形，分析诊断出汽油机点火系统故障点部位。同时介绍该系统在分电器在试验台上的实验情况。结果表明，该系统诊断断点系故障快速准确。     

在汽油机上实施HCCI的技术策略

均质混合气压燃(HCCI)燃烧方式，是一种克服常规柴油机和汽油机缺点、集常规汽油机和柴油机优点于一体的新概念燃烧。本文分析了汽油机实施HCCI的可行性，介绍了HCCI发动机实用化所面临的问题，提出了双工作模式的折衷方案：在中低负荷工况实施HCCI，而在大负荷工况和冷起动工况恢复常规发动机工作方式。推荐可变压缩比(VCR)方案、可变废气再循环率(EGR)方案、可变排气门关闭时刻方案，以及废气再循环滚流分层充气方案等。为尽快在汽油机上实施HCCI燃烧方式指出了技术方向。     

缸内直接喷射式汽油机点火稳定性的数值分析

缸内直接喷射式汽油机的一个显著特点是依靠火花塞点燃喷入缸内的汽油油束。由于缸内混合气浓度极不均匀，所以其点火及火焰传播过程与普通均质燃烧式发动机有很大的不同。火焰核心的稳定形成及初始火焰发展对缸内的整个燃烧过程有极其重要的影响。本文利用二维两相混合模型模拟喷雾过程，利用一个详细的准维模型模拟火花塞的点火过程，并采用特殊处理方法使两个子模型相匹配，计算了缸内直接喷射式汽油机从喷雾到形成稳定火核的全过程，分析了多种因素对点火稳定性的影响，尤其是对涡流比、点火时刻和喷油定时之间的适当配合进行了模拟分析。计算结果对优化实验有明显的指导作用。     

利用快速压缩膨胀机研究火花点火LPG发动机的燃烧过程

利用快速压缩膨胀机对火花点火LPG发动机的燃烧过程进行了模拟与测量，分析了混合气浓度，点火提前角，压缩比以及燃烧室形状等对LPG燃烧过程的影响，可供汽油机改装成汽油／LPG双燃料发动机的参考。     

Stoichiometric H2ICEs with water injection

For the most part, gasoline engines operate close to stoichiometry because of the high power density and the easy after treatment through the very well established three-way catalytic converter technology. The lean burn gasoline engine suffers major disadvantages for the after treatment still requiring aggressive research and development to meet future emission standards more than for the lower power density compensated by the better fuel conversion efficiency running lean. Hydrogen engines are usually run ultra-lean to avoid abnormal combustion phenomena and possibly to avoid the emission of nitrogen oxides without the difficult non-stoichiometric after treatment. While the ultra-lean combustion of hydrogen may reduce the formation of NOx within the cylinder but makes the power density very low, the only lean combustion of hydrogen requires after treatment for NOx reduction. The suppression of abnormal combustion in hydrogen engines has been a challenge for the three regimes of abnormal combustion, knock (auto ignition of the end gas region), pre-ignition (uncontrolled ignition induced by a hot spot prior of the spark ignition) and backfire (premature ignition during the intake stroke, which could be seen as an early form of pre-ignition). Direct injection and jet ignition coupled to port water injection are used here to avoid the occurrence of all these abnormal combustion phenomena as well as to control the temperature of gases to turbine in a turbocharged stoichiometric hydrogen engine.     

Evolution,challenges and path forward for low temperature combustion engines

Universal concerns about degradation in ambient environment, stringent emission legislations, depletion of petroleum reserves, security of fuel supply and global warming have motivated research and development of engines operating on alternative combustion concepts, which also have capability of using renewable as well as conventional fuels. Low temperature combustion (LTC) is an advanced combustion concept for internal combustion (IC) engines, which has attracted global attention in recent years. LTC concept is different from the conventional spark ignition (SI) combustion as well as compression ignition (CI) diffusion combustion concepts. LTC technology offers prominent benefits in terms of simultaneous reduction of both oxides of nitrogen (NO_x) and particulate matter (PM), in addition to reduction in specific fuel consumption (SFC). However, controlling ignition timing and combustion rate are primary challenges to be tackled before LTC technology can be implemented in automotive engines commercially. This review covers fundamental aspects of development of LTC engines and its evolution, historical background and origin of LTC concept, encompassing LTC principle, its advantages, challenges and prospects. Detailed insights into preparation of homogeneous charge by external and internal measures for mineral diesel and gasoline like fuels are covered. Fuel requirements and fuel induction system design aspect for LTC engines are also discussed. Combustion characteristics of LTC engines including combustion chemistry, heat release rate (HRR), combustion duration, knock characteristics, high load limit, fuel conversion efficiencies and combustion instability are summarized. Emission characteristics are reviewed along with insights into PM and NO_x emissions from LTC engines. Finally, different strategies for controlling combustion rate and combustion timings for gasoline and mineral diesel like fuels are discussed, showing the way forward for this technology in future towards its commercialization.     

微机控制汽油机点火系以提高点火能量

本文介绍了一种利用微型计算机控制汽油机点火系以提高点火能量的方法,用微机控制初级电路导通的时间,同时减小初级回路的电阻,使得断开电流增大而又不致烧坏点火线圈,提高了点火能量以及最大次级电压,从而可增大火花塞间隙,试验表明用此方法可以燃烧更为稀薄的混合气,使油耗率大为下降。     

Active fuel design—A way to manage the right fuel for HCCI engines

Homogenous charge compression ignition (HCCI) engines feature high thermal efficiency and ultralow emissions compared to gasoline engines. However, unlike SI engines, HCCI combustion does not have a direct way to trigger the in-cylinder combustion. Therefore, gasoline HCCI combustion is facing challenges in the control of ignition and, combustion, and operational range extension. In this paper, an active fuel design concept was proposed to explore a potential pathway to optimize the HCCI engine combustion and broaden its operational range. The active fuel design concept was realized by real time control of dual-fuel (gasoline and n-heptane) port injection, with exhaust gas recirculation (EGR) rate and intake temperature adjusted. It was found that the cylinderto- cylinder variation in HCCI combustion could be effectively reduced by the optimization in fuel injection proportion, and that the rapid transition process from SI to HCCI could be realized. The active fuel design technology could significantly increase the adaptability of HCCI combustion to increased EGR rate and reduced intake temperature. Active fuel design was shown to broaden the operational HCCI load to 9.3 bar indicated mean effective pressure (IMEP). HCCI operation was used by up to 70% of the SI mode load while reducing fuel consumption and nitrogen oxides emissions. Therefore, the active fuel design technology could manage the right fuel for clean engine combustion, and provide a potential pathway for engine fuel diversification and future engine concept.     

小型通用汽油机生产和技术发展情况

本文对国内外小型通用汽油机的生产现状和技术发展进行了报导，特别对改善发动机性能方面所采取的措施如提主压缩比，改进点火系统，采用新材料，新结构，优化设计和降低排放等方面都进行了论述。     

汽油机燃烧过程模拟计算及爆震预测

将计算焰前反应的化学反应动力学模型与燃烧模型及湍流火焰传播模型相结合,建立了含有碳氢燃料焰前反应的简易化学动力学模型的汽油机双区燃烧模型。用该模型能较好地模拟汽油机燃烧过程,并能实现爆震预测,研究影响爆震发生的诸多因素。采用此模型对４９２ Ｑ Ａ 汽油机进行模拟计算的结果与试验结果能较好地吻合,证明了该模型的可行性。     

汽油均质混合气柴油引燃(HCII)燃烧特性的研究

为探索大幅度提高汽油机热效率的途径，采用了一种汽油均质混合气柴油引燃(HCⅡ)的燃烧方式，结合发动机性能试验与可视化试验对HCⅡ的燃烧特性进行了初步研究。研究结果表明：HCⅡ燃烧方式的热效率显著高于汽油机，可以达到甚至超过柴油机的水平；在汽柴油质量比大于0．5时可保证无烟燃烧；随汽柴油比的增加，滞燃期增长，着火点位置由中心向周边拓展。