研究了可变滚流结构的稀薄燃烧特性。主要讨论了可变滚流结构对发动机稀薄燃烧时燃油经济性和排放特性的影响。结果表明 :在稀薄燃烧情况下 ,发动机负荷大小对 CO排放的影响不大 ,CO排放始终保持在 0 .5 %以下 ;HC排放则具有相似的变化趋势 ,但排放量随负荷增加而略有增加 ;负荷对 NOx 排放的影响主要表现在空燃比为 13～ 18的范围内 ,负荷越大 ,NOx 排放越大 ;对空燃比小于 13或大于 18的 NOx 排放影响较小。阀片位置 (或滚流比 )对发动机稀燃状态 CO排放的影响很小 ,而对 HC和 NOx排放则存在一定影响。在稀薄燃烧条件下 ,滚流运动更有利于改善低速高负荷时的燃油经济性。 The lean combustion characteristics of the variable tumble flow structure were investigated. The effect of variable tumbling structure on the fuel economy and emission characteristics of lean burn engine is mainly discussed. The results show that under lean burn condition, the effect of engine load on CO emission is insignificant and CO emission remains below 0.5%. HC emission shows a similar trend, but the emission increases slightly with the increase of load ; The impact of load on NOx emission is mainly manifested in the range of air-fuel ratio of 13 to 18, the greater the load, the greater the NOx emission; the less impact of the air-fuel ratio of less than 13 or greater than 18 NOx emissions. The valve position (or tumble ratio) has little effect on CO emissions from the lean combustion engine, while it has some effect on HC and NOx emissions. Under lean burn conditions, tumble motion is more conducive to improving fuel economy at low speeds and loads.