【作者】 王天友；

【导师】 刘书亮；

【作者基本信息】 天津大学 ， 动力机械及工程， 2003， 博士

【摘要】 节约燃油消耗、减少温室效应气体排放以及进一步改善汽车尾气中有害气体的排放是广大内燃机工作者和汽车工业的科学家们目前所面临的最大挑战之一。汽油机燃烧稀混合气是降低有害尾气排放、减少燃油消耗率的有效途径。突破进气道喷射发动机不依靠喷射生成混合气，只能通过组织缸内空气运动来形成这一传统观点，本文提出了在进气道喷射发动机上通过可控喷油形成可控的缸内准均质稀混合气，进而实现快速准均质稀薄燃烧的新概念。实现这种可控喷油概念的技术支撑就是二次喷油专利技术。依照这一新的概念，在一台未作任何结构改动的四缸、16气门产品发动机上，成功地实现了准均质稀薄燃烧。研究结果表明：两次喷油可拓展发动机稀燃极限1.5-2个空燃比单位，最高达23.5；发动机燃油消耗同原电喷发动机相比可降低19.1%；整个空燃比范围内，经过优化的两次喷油稀燃的最低油耗较单次喷油稀燃下降6.5%左右，各种排放物机内生成量均有大幅度下降。本研究运用三效催化器+空燃比优化控制技术，利用三效催化器能一定程度降低NOx排放的特点，控制发动机在优化空燃比下工作，将稀燃后排气中剩余不多的NOx进一步催化。同时，本研究也成功地运用了由原位合成技术制作的分子筛堇青石整体式分子筛催化器，去除稀燃NOx排放。稀燃发动机台架实验结果表明，催化剂抗硫中毒、抗高温以及抗水蒸气能力较强；最大NOx转化效率达74.4%；最大NOx转化率排气温度点在400℃附近。最后综合采用机内净化和排气后处理并行策略，即稀燃、快燃（滚流）、推迟点火的可控燃烧新方案，结合分子筛稀燃催化器，在稀燃发动机典型工况下，在保证燃油经济性较原机改善14.8%时，NOx的排放大幅降低。更多还原

【Abstract】 Reduction of the fuel consumption, the carbon dioxide emission and the exhaust gas emissions is one of the major challenges that engineers and scientists in the automotive industry are currently facing. Lean burn concepts such as the homogenous A/F mixture gasoline lean burn engine or the direct injected gasoline engine may point the way of future automobile developments. A new point of view that the mixture preparation processes can been controlled by controlling fuel injection in multi-port fuel injection engine, in contrast to the traditionally point of view that the mixture formation is only controlled by induction flow. The technology of twice electronic fuel injection in premixed lean burn gasoline engine can realize the new controlling fuel injection concept. Through adjusting the controlling fuel injection--regulations of the two injection timings and proportions, an adequate air and fuel charge stratification was produced-we call it quasi-homogenous mixture and the lean burn was successfully realized in a product 4-valve S.I. engine whose structures aren’t changed at all. Investigations show that twice electronic fuel injection can make the lean limit(A/F) increase by 1.5-2 units; the fuel consumption and exhaust emissions are improved remarkably, in partial load, compared with the product 4-valve S.I. engine , the fuel consumption decreases by about 19.1%. On the other hand, the fuel consumption of quasi-homogenous mixture lean combustion decreases by about 6.5% compared with homogenous lean mixture combustion.Three-ways catalyst (TWC)+ optimizing AFR technology is used to remove NOx emissions in oxygen containing exhaust gas. Lean-burn engine is operated at air-fuel(A/F) ratios of 21:1 and above, in addition, ignition is delayed, as a result of these technique, the NOx emissions are very low. Then TWC reduces NOx at a certain extent and almost all HC and CO. On the other hand, a new catalyst for selective reduction of NOx is also investigated in this thesis. Zeolites are in-situ synthesized on the surface of honeycomb-shaped cordierite under hydrothermal conditions. Investigations on a lean burn engine show that NOx can be removed by using HC and CO in the exhaust gas as reducing agents. When the catalyst is used , the rate of NOx conversion can reach a maximum of 74.4% at 400℃. Investigations also show that the catalyst shows good heat resistance in the presence of water and demonstrates high capability for mitigating SOx poisoning. In the end, a novel way controlling combustion is employed in a 1.342L S.I.engine, in which lean-burn, fast burn (tumble) and delay ignition make the engine provide much cleaner exhaust gas than that of a conventional premixed S.I. engine. Moreover, the de-NOx catalyst is mounted on the exhaust pipe. All these methods make it possible for emissions of lean-burn engines to completely meet the strict NOx regulations such as Euro Ⅱ, even Euro Ⅲ, at the same time, the fuel consumption decreases by 14.8%.更多还原