开阀喷射模式对进气道喷射式汽油机性能的影响

采用台架试验和数值计算的方法研究了开阀喷射模式对发动机性能的影响规律。研究结果表明:在20%节气门开度下,较早的喷油时刻与较晚的喷油时刻相比,功率升高了0.2kW,HC排放降低了30×10~(-6);当节气门开度达到100%时,由于进气气流和机体温度的影响使得喷油时刻对动力性和排放性能的影响可以忽略;处于20%节气门开度时未挥发燃油最大比例大约占总喷油量的50%,而在100%节气门开度下未挥发燃油仅占15%左右,可见燃油未完全挥发是造成开阀喷射模式时发动机性能下降的主要原因,提高开阀喷射模式下发动机燃油挥发性能是提升发动机性能的主要途径。

Effect of Open Valve Injection Mode on PFI Gasoline Engine Performance

In view of the different characteristics of closed valve injection(CVI) and open valve injection(OVI), the effect of OVI on the performance of a port fuel injection(PFI) gasoline engine was studied by bench test and numerical simulation. Results show that at 20% of the throttle valve opening degree, the earlier injection timing can make engine output power increased by 0.2 kW and the HC emission decreased by 30×10-6 compared with the later injection timing However, when the throttle valve opening degree is up to 100%, the injection timing on engine power and emission is negligible due to the influence of intake airflow and cylinder temperature. In addition, at 20% of the throttle valve opening degree, the proportion of non volatilized fuel is about 50% of the total fuel injection quantity while at full throttle, the non volatilized fuel accounts for only 15% of the total fuel injection quantity. It can be seen that no completely volatilized fuel is main reason for the decline in OVI engine performance. Therefore, improving fuel volatility is the main way to improve the performance of OVI engine.