基于优化动力技术的多缸汽油机均质混合气压燃/火花点火模式循环变动

Variation on Multi-cylinder Gasoline HCCI /SI Engine Based on Optimized Kinetic Process Technology

采用优化动力技术实现了四缸汽油机的均质混合气压燃(HCCI)稳定燃烧;统计分析了火花点火(SI)与HCCI模式的切换点,2种模式下在相同负荷时缸内、缸间的循环变动特点,以及HCCI燃烧向高负荷范围拓展的限制条件和解决方法.结果表明:在1 400 r/min的较低转速下,适当增加切换点负荷,可使切换后的HCCI燃烧更为平稳;当负荷相同时,HCCI模式下燃烧参数的循环变动系数显著低于SI模式,且其平均指示压力在缸内的循环变动系数小于2.5%,缸间的循环变动系数小于3.0%;各缸之间的燃烧参数存在规律性的差异,可采用重新布置进气管路和冷却水循环管路来解决;拓展HCCI负荷范围,必须采取降低进气温度和采用废气再循环的措施,以抑制着火时刻过早和放热率过大的情况发生.

Stable homogeneous charge compression ignition （HCCI） combustion on a commercial gasoline engine was realized through the optimized kinetic process technology. Statistical analysis method was adopted to analyze the spark ignition （SI）-HCCI switching process at different load point. And then the same method was used to analyze cycle-to-cycle and cylinder-to-cylinder variation characteristics for these two modes under the same load. Finally, the restrict conditions and solutions for HCCI load expansion were discussed. The results show that, for the switching process at low engine speed 1 400 r/min, properly increasing load can make switching process more smoothly; at the same load, each combustion parameter variation in HCCI mode is remarkably less than that of parameters in SI mode, the cycle-to-cycle variation of indicated mean effective pressure is less than 2.5 % and the cylinder-to-cylinder variation is less than 3.0 %. The statistics also show that each cylinder-to-cylinder combustion parameter has regular difference;this trouble can be solved through the rearrangement of intake manifold and coolant circulation. Mean- while, in order to expand the HCCI load, decreasing the inlet air temperature and exhaust gas recirculation strategies should be used to retard the beginning of combustion and slow the rate of heat release.