【摘要】 通过缸内直喷两次喷射的方法,均质充量压缩着火(HCCI)燃烧在稳态工况下能够被有效地控制。对于瞬态工况,不仅要求对燃烧能够灵活控制,而且必须具有快速的响应特性。研究了HCCI发动机在转速和负荷发生改变时的瞬态特性。结果表明,在发动机转速改变时,HCCI燃烧具有自平衡特性。通过调节两段喷油比例,可以抵消由于诸如转速变动等工况变化引起的燃烧相位改变。同时改变喷油策略和循环供油量成功地实现了负荷的调节,调节过程在一个发动机循环内完成。通过优化负荷调节过程的中间喷油策略,可以进一步平滑动态过程,使燃烧波动得到抑制。发动机的响应特性显示,由负阀重叠(Negative Valve Overlap,NVO)实现的HCCI燃烧对部分边界调节不敏感,通过调节喷油策略能够提高HCCI燃烧的鲁棒性。更多还原

【Abstract】 HCCI combustion can be controlled effectively by gasoline direct injection with NVO in the steady state.For transient process,both control flexibility and rapid response are needed.In this paper,the combustion analysis of dynamic process was conducted.From the test result,HCCI combustion showed the self-balance capability to the variation of engine speed.By adjusting the injection ratio of two-stage fuel injection,the auto-ignition timing and combustion rate could be controlled flexibly to adapt combustion phase change during the mode transition like speed variation.Smooth transition during load change was realized by adjusting the fuel supplying amount and the injection strategy simultaneously.The transition was completed within one cycle.Furthermore,by optimizing injection during transition,the process was smooth and the fluctuation was eliminated.The response characteristics revealed that HCCI combustion by NVO was insensitive to some engine operation conditions.Adjusting the injection strategies can enhance the robustness of HCCI combustion.更多还原