不同点火时刻取值方式对CNG发动机燃烧循环变动特性的影响

Influence of Different Ignition Timing on Control Strategies Cyclic Variations in a CNG Engine

首先讨论点火时刻对平均指示压力变动系数的影响,同时对比了采用固定点火时刻和采用平均指示压力变动系数最小值的点火时刻时,不同因素对CNG发动机燃烧循环变动特性的影响规律.结果表明,在其他工况参数与控制参数不变时,存在平均指示压力变动系数最小的点火时刻.采用固定点火时刻研究循环变动特性规律时,点火时刻取值的差异会导致CNG发动机燃烧循环变动特性规律的差异;采用平均指示压力变动系数最小值点火时刻时,燃烧循环变动特性规律具有唯一性.

The influence of ignition timing on coefficient of variation of indicate mean effective pres- sure （CoVIMEP） was investigated. The influence of different factors on cyclic variations is compared with fixed ignition timing and minimum COVIMEP （MCV） ignition timing. Experimental results show that a cer- tain ignition timing could be found where COVIMEP is the minimal under the given operation condition. Under fixed ignition timing conditions, different ignition timings will give different cyclic variations characteristics. Cyclic variations characteristics are unique by using MCV ignition timing.