【作者】 刘伟；

【导师】 刘胜吉；

【作者基本信息】 江苏大学 ， 动力机械及工程， 2015， 硕士

【摘要】 近十年我国通用小型汽油机产业取得了飞速的发展,已成为世界上通用小型汽油机主要生产国与出口国。但采用机内净化技术的国内通用小型汽油机难以在批量生产中满足美国EPA第Ⅲ阶段排放法规要求,这已是行业发展的技术瓶颈之一,而采用机外净化措施能使整机排放满足EPA法规要求,但这不仅使得发动机成本增加,同时降低了发动机安全性。因此系统开展进排气、供油和燃烧过程研究,开发高性能低排放通用小型汽油机产品具有重要的实用价值。以市场占有率较高的188F汽油机为样机,以满足国际最为严格的美国EPA第Ⅲ阶段排放法规为目标,用试验和模拟分析相结合的方法开展进排气、供油和燃烧过程研究。分析了压铸气缸盖的进排气道结构特性和进排气道流道的截面积变化,在进排气系统稳流试验台上试验得出改进压铸气缸盖进排气道提高进排气流量的技术方案,在满足压铸工艺的前提下,优化后的进、排气道流通系数比原机分别增大了20.3%和16.1%;通过对空气滤清器进气道的优化设计,进气流量比原机增大了4.0%;用优进排气系统化后的汽油机台架试验表明:标定转速全负荷时的扭矩增大了1.87N·m,燃油消耗率降低了8.1g/(kW·h),不同负荷工况汽油机HC和CO排放降低,NOX排放略有增大。用Ricardo Wave软件模拟了混合气浓度和点火提前角对不同负荷工况下汽油机动力性、经济性、各种有害排放物的影响,结合试验得出了188F汽油机不同负荷、转速工况主要排放污染物随混合气浓度变化以及点火提前角变化的量化关系,依据法规的排放限值,形成了低排放高性能通用小型汽油机理想油气混合比特性和理想点火提前角特性。试验确定了188F汽油机不同负荷工况最佳油气混合比方案,汽油机CO、HC+NOX比排放值分别为347.5g/(kW·h)和6.91g/(kW·h)。再通过优化点火提前角,使汽油机HC+NOX比排放值降到6.23g/(kW·h)。劣化试验后CO和HC+NOX比排放值分别为312.5g/(kW·h)和7.10g/(kW·h),远低于美国EPA第Ⅲ阶段排放限值,汽油机批量生产排放达标。研究工作为国内开发低排放高性能通用小型汽油机提供了机内净化的技术路线。更多还原

【Abstract】 The non-road SI engine industry in China has achieved rapidly development in the last ten years and China has become the world major producers and exporters of the non-road SI engine. But the use of the interior purification technology in the domestic non-road SI engine can hardly meet the US EPA phase-Ⅲ emission standard, and it has become one of the technical bottleneck in the development of the industry. Some external purification technologies can make the whole machine emission meet EPA emission regulations, but it may increase the engine cost, and reduce the engine safety. Therefore, developing a high performance, low emission non-road SI engine product by optimizing the air intake system, fuel supply system and combustion process would make an important practical value.188F gasoline engine which has a higher market share is the research prototype, and the aim of the research is to meet the most stringent US EPA phase-Ⅲ emission standard. Combination methods of simulation analysis and experimental method were used on the optimization of intake and exhaust system, fuel supply and combustion process research. The structural characteristics and the cross-sectional area change of the intake and exhaust airway were analyzed, the best optimized scheme for the intake and exhaust system with the technology meeting the die-casting technology was got by the steady flow test bench. Compared with the original engine, the intake and exhaust airway flow coefficient increased 20.3% and 16.0% respectively; with the optimized design for intake flow path, the intake flow was 4.0% higher. The engine bench test result for the optimized intake and exhaust systems shows: when the engine was working at the full load, the torque increased by 1.87 N·m, and the specific fuel consumption decreased by 8.1g/(kW·h), and the HC and CO emission at different load reduced, while NOX emissions slight increased. The effect of gasoline engine power, economy, and emissions changed with the different mixture concentration and the advanced ignition at different loads. And these results were simulated by Ricardo-Wave software. Quantify the relationship of the engine performance change with the different mixture concentration and the advanced ignition by engine bench test. A low-emission high performance non-road SI engine with ideal air ratio characteristics and ideal ignition timing characteristics were got according to regulatory emission limits. The brake specific emission of CO, HC+ NOX of the 188 F gasoline engine were 347.5g/(kW·h) and 6.91g/(kW·h). At the same time, optimal mixing excess air ratio programs were determined. The brake specific emission of HC+NOX dropped to 6.23g/(kW·h) with timing the ignition advanced angle. After the deterioration test, the brake specific emission of CO and HC+NOX were 312.5g/(kW·h) and 7.10g/(kW·h), it is far below the US EPA Phase Ⅲ emission limits. Research for the development of low-emission high-performance non-road SI engine can provides a referenced technical route for other non-road SI engine in domestic.更多还原