稀燃发动机是指能燃用空燃比为18∶1或更低的混合气的汽油机。当前各国汽车界正致力于解决排气净化及节约燃料等问题,从而稀燃发动机概念得到普遍重视。如所周知,燃用稀混合气能使燃烧完全,能使排气中的 HC 和 CO 的浓度降低,油耗减少。然而,若燃用空燃比为16∶1左右的稀混合气,排气中的氧化氮(NOx)的浓度反而最 A lean burn engine is a gasoline engine that can burn a mixture with an air / fuel ratio of 18: 1 or lower. At present, the auto industry in various countries is devoted to solving the problems of exhaust gas purification and fuel saving, so that the concept of lean-burn engine is universally valued. As we all know, burning with lean mixture can make the combustion complete, can exhaust the concentration of HC and CO decreased, reducing fuel consumption. However, when a lean mixture with an air-fuel ratio of about 16: 1 is used, the concentration of nitrogen oxide (NOx) in the exhaust gas is rather the highest