基于米勒循环的混动专用发动机开发

Development of Hybrid-Dedicated Engine based on Miller Cycle

对奥托循环、米勒循环以及米勒循环加进气遮蔽(Masking)三种方案的缸内气流、混合气浓度以及燃烧性能进行对比分析,结果表明:米勒循环由于型线的影响一定程度上恶化了缸内气流运动与燃烧性能,而Masking可大幅度提升滚流比,改善混合气浓度,增加湍动能,改善燃烧性能。对奥托循环和Masking方案进行了试验研究,结果显示:相比奥托循环,Masking方案外特性最大扭矩降低12%,额定功率降低3%,外特性油耗平均降低14.6%,部分负荷工况油耗平均降低7.1%。在Masking方案的基础上引入冷却EGR,发动机最高热效率达到38.6%。

Comparative analysis of in-cylinder air flow,mixture concentration and combustion performance was conducted based on three schemes of the Otto cycle,Miller cycle and Miller cycle with inlet cover(Masking).The results showed that the Miller cycle deteriorated in-cylinder air flow and the combustion performance to some extent due to the profile.However,Masking could greatly enhance the tumble ratio,improve the mixture concentration,increase the turbulent kinetic energy,and hence improve the combustion performance.Then the Otto cycle and Masking solution were further studied by the experiment.With the Masking,the torque of wide open throttle decreased by 12%,the rated power decreased by 3%,and BSFC decreased by 14.6%and 7.1%at average under wide open throttle and partial load conditions respectively.The Masking solution can further make the maximum thermal efficiency reach up to 38.6%after introducing the cooling EGR.