蒸汽压力对发动机冷启动与排放的影响

Effect of steam pressure on cold start and emissions of engine

油品的差异会对启动产生很大影响,尤其是低蒸汽压力(即RVP)的油会导致发动机冷启动困难甚至发动机冷机不着车。随着排放法规的日趋严格,加之启动阶段的排放在整个测试循环所占比重较大,研究汽油RVP的差异对启动和排放产生的影响有十分重要的指导意义。通过试验对比两种不同蒸汽压力的燃油在一系列温度点启动时的差异,试验结果表明低RVP值燃油相对高RVP值燃油挥发性差,导致实际进入汽缸参与燃烧的油比高RVP值要少,导致混合气偏稀、转速不稳、排放恶化,但对油耗无明显影响。

The difference in oil will have a significant impact on the start,especially the low vapor pressure（ ie,RVP）of the oil will lead to the cold start of the engine. As the emission regulations become more stringent,and the proportion of emissions in the start-up phase is larger than that in the whole test cycle,it is very important to study the influence of gasoline RVP on start-up and emission. The experimental results show that the fuel volatility is poor in low RVP value of the fuel,resulting in the combustion of oil volume is less than the high RVP value. Issues in partial thin of mixed gas,unstable speed and deterioration of emissions,but there is no significant impact on fuel consumption.