LPG电控喷射冷起动循环的着火及HC排放影响因素分析

分析了电喷LPG发动机冷起动过程中影响着火及HC排放的主要因素。试验在一台四冲程、水冷125mL单缸电喷发动机上进行。试验结果表明：LPG发动机冷起动混合气的浓度相当于稳定燃烧混合气浓度的1．5倍左右，比汽油机稀，HC排放也低；随着混合气变稀，首次着火循环逐渐推迟；高起动转速是发动机冷起动可靠的一个主要保障因素；适当提前点火和增大火花塞间隙有利于降低冷起动循环的首次着火循环数；环境温度是影响冷起动过程的一个主要参数。

Key Factors Affecting Ignition and HC Emission During Cold-start in a LPG EFI Engine

In this paper,key factors affecting ignition and HC emission during cold start in a LPG EFI engine are analyzed based on the test on a four stroke,water cooled,125mL single cylinder SI engine with EFI system Test results show that the LPG mixture in cold start is 1 5 times as rich as that in normal running,but is still leaner than that of gasoline engine,so HC emission of LPG engine at start condition is lower than that of gasoline engine The first firing cycle is postponed when the mixture becomes lean High cranking speed for cold starting is a main factor to ensure the successful firing and combustion The proper advanced spark timing and wider spark gap are helpful in improving cold starting And the ambient temperature is also an important factor for cold starting