稀薄燃烧发动机改型设计及正时策略优化

基于某高速汽油机,对燃烧室结构、燃油喷射特性、凸轮型线改型设计为稀薄燃烧发动机。提出利用响应面模型对正时策略进行分析和优化的研究方法,并建立利用响应面进行多目标优化计算的流程。以提高有效功率和降低有效燃油消耗率为优化目标,以点火正时、空燃比和进排气正时为设计变量,建立了发动机性能与响应面耦合优化模型。分析与试验结果表明:较标准混合比燃烧时,稀薄燃烧发动机的进排气提前角减小,点火正时提前,最低燃油消耗率下降3.9%,最大功率提升9.7%;同时利用响应面优化方法提高了优化效率。

Lean Burn Engine Retrofit Design and Timing Strategy Optimization

Based on a high-speed gasoline engine,the combustion chamber structure,fuel injection characteristics and cam profile are redesigned as a lean burn engine.A research method of timing strategy analysis and optimization using response surface model is proposed and the process of multi-objective optimization calculation by using response surface is established.To improve the effective power and reduce the effective fuel consumption rate,the engine performance and response surface coupling optimization model is established by taking ignition timing,air-fuel ratio and intake and exhaust timing as design variables.The analysis and test results show that compared with standard mixture ratio combustion,with reduced inlet and exhaust advance angle and advanced ignition timing,the minimum fuel consumption of the lean-burn engine is reduced by 3.9%and the maximum power is increased by 9.7%;at the same time,the method of response surface optimization improves the optimization efficiency.