增压柴油机采用多级可变文曲利管式进气系统的实验研究

The Researching of Diesel Multi-Variable Venturi Intake Pipes System

EGR技术应用在增压柴油机上出现了进排气压逆差导致应用有限的现象。本文采用将原有进气系统改造成由多个文曲利管并联组成的进气系统解决此问题。该系统一方面可由不同文曲利管之间的组合排列达到适应随工况变化的可变进气目的;另一方面,可以借助多个文曲利管的喉部压降能力吸引更多排气达到扩大EGR率的效果。通过流量模拟测试实验获得,采用MVVIPS较传统的串联式和分流式文曲利管系统都取得了更大的流通能力和压降能力;通过内燃机综合测试台架可知,采用MVVIPS系统后,试验用柴油机过量空气系统在不同转速下有着不同的变化;相比较原机的EGR系统,MVVIPS系统的EGR率在每个试验工况下都得到了不同程度的提高;动力性和经济性都在低、中转速下有小幅升高,但在高转速下与原机相差不大;根据稳态十三工况排放数据显示,采用MVVIPS系统后,NOx排放得到了有效控制,CO和微粒排放变化不大,HC排放在怠速及低工况范围内有着较明显的降低。

The application of EGR technology in the turbocharged diesel engines was limited by the deficit of exhaust pressure.We solved this problem via replacing the original air intake system by venturi tube parallel pipeline.On one hand,different arrangements of venturi tubes were adapted to various working conditions;on the other hand,the throat pressure drop of venturi tubes could be used to attract more exhaust for the rising of EGR rate.The flow simulation test proves that the MVVIP system can achieve better circulation and pressure-drop than traditional series and shunt venturi tube.The engine bench test shows that the excess air ratio changes under different rotating speeds;the EGR rates increase under all working traditions;the dynamic performance slightly changes;fuel consumption achieves a maximum reduction by 2.2%.NOx emission decreases,and HC emission declines significantly under idle speed and low load.CO and particle emissions vary slightly.