四气门发动机可变涡流稀薄燃烧特性研究

A STUDY ON THE EFFECT OF SWIRL-VARIABLE DEVICE ON LEAN-BURN 4-VALVE SI ENGINE

本文研究了可变涡流对四气门发动机稀薄燃烧特性的影响情况。在稀薄燃烧情况下,发动机负荷大小对CO和HC排放的影响不大,对NOx排放的影响主要表现在对13～17空燃比范围内NOx排放的影响,负荷越大,NOx排放越大;对空燃比小于13或大于17以后的NOx排放影响较小。阀片位置对发动机排放特性的影响较小,对发动机的燃油经济性存在一定影响,这是因为不同阀片位置的进气涡流比不同所致,同时也表明较强的涡流运动对燃油经济性更有利。涡流运动在不同转速条件下对发动机燃油经济性的影响情况不同,它更有利于改善低速条件下的燃油经济性。

The effect of variable swirl on lean burn combustion of 4-valve SI engine was studied in this paper. In the condition of lean burn combustion, engine-load has little effect on CO and HC emissions, and NOx emission increases with engine-load at the A/F ratio of between 13 and 17. Out of the domain, engine load has little effect on NOx emission. The effect of swirl valve position (or swirl ratio), on lean burn combustion engine emission was small. So far as the fuel consumption, position 3 was less than position 2, that is to say, stronger swirl motion can improve efficiency of SI engine more. The effect of swirl motion on fuel economy varies with engine speed and it is more efficient at lower speed than higher speed.