基于首次着火循环的低温冷起动特性(Ⅱ)

Cold Start Characteristics at Low Temperature Based on the Analysis of the First Firing Cycle

在一台125 cm3单缸风冷电控喷射LPG发动机上进行了单循环冷起动实验研究．通过分析发动机最初几个循环的瞬时转速、缸压以及HC排放,得到了发动机首次着火循环冷起动时的燃烧及排放情况．在对首次着火循环分析的基础上,研究了过量空气系数、环境温度、点火提前角和蓄电池电压对LPG发动机首次着火循环燃烧情况的影响．结果表明,蓄电池电压影响发动机冷起动首次着火循环的HC排放,同时对首次着火循环的起动转速也有影响;点火提前角对首次着火循环起动转速影响较大,但对单循环冷起动时的HC排放影响不大;LPG发动机首次循环可靠起动的最佳点火提前角为上前10°CA．

The first firing cycle （FFC） at cold-start is investigated in one 125 cm^3 single cylinder air-cooled EFI engine fuelled with LPG. By analyzing instantaneous speed, cylinder pressure and HC emissions of the first cycle at cold-start, the characteristics of combustion and emissions are investigated. Based on the first firing cycle analysis, the effects of air fuel ratio, environmental temperature, spark advance angle and battery voltage on LPG engine＇s FFC are tested. The results show that the initial battery voltage has a great influence on HC emissions of the FFC. Battery voltage also affects cranking speed of the FFC. The spark advance angle has a great influence on start-up speed, but has little influence on engine＇s HC emissions of the FFC. There is an optimal spark advance for the successful cold start of the LPG engine which is 10 ℃A BTDC.