可变滚流与二次喷油对火花点燃式发动机稀燃特性影响的研究

本文研究了可变滚流与二次喷油技术对发动机稀燃特性的影响。研究发现:1)在三种滚流比情况下,发动机比油耗随二次喷油比例的增加,呈下降趋势,说明在缸内只存在滚流运动的情况下,采用较大比例的二次喷油量可以获得更好的燃油经济性。2)喷油正时明显影响发动机燃油耗,在三种滚流比情况下,最低油耗点所对应的喷油正时按照T1、T2和T3顺序依次提前;负荷较大时,对应的最低油耗点喷油正时也相应有所提前。3)增强进气滚流运动可以改善发动机低速工况条件下的燃油经济性和排放特性,但应避免可变滚流机构对燃油喷注的阻隔作用。

A Study on the Effect of Variable Tumble and Twice Electronic Fuel Injection on the Performance of a 4- valve Lean Burn SI Engine

The effect of variable tumble and twice electronic injection that were adopted together on the performance of a 4-valve SI engine was studied. Firstly, large second fuel injection leads to better fuel economy when there is only tumble motion in the cylinder. Secondly, second fuel injection timing has obvious effect on the fuel consumption. At the three tumble valve positions, the second fuel injection timing advancements for the best fuel economy increased according T1, T2 and T3 positions and with the increase of load. Thirdly, although the strengthened tumble motion can improve fuel consumption when the engine is running at lower speed and load, the barring effect on the fuel spray must be avoided.