林业机械中通用小型汽油机排放控制及效果分析

Emission Control and Effect Analysis of General Small Gasoline Engine for Forestry Equipment

以单缸风冷四冲程的通用小型汽油机为研究对象,采用开环控制方式,预先通过万有特性试验测定各个特定工况点的最佳进气氧体积分数控制量,生成进气控制初始脉谱表;通用小型汽油机实际运行时,根据测得的工况参数值确定运行工况,通过查进气控制脉谱表确定进气氧体积分数控制量,实现通用小型汽油机的富氧进气排放控制。选择2000、3000 r/min两个常用转速,分别采用常态进气和富氧进气两种方式,进行HC、CO、NOx排放的负荷特性验证性试验。验证结果表明:与常态进气相比,采用富氧进气控制方式,试验用通用小型汽油机的HC和CO排放明显降低,但NOx排放存在上升趋势;2000、3000r/min条件下,HC排放的最低值下降率分别为18.26%和14.02%,CO排放的最低值下降率分别为16.87%和17.78%,NOx排放的最低值增长率分别为10.61%和8.70%。

We focused on generating the initial intake control map of the general single -cylinder air-cooled four stroke small gaso-line engine by testing the best intake oxygen concentration for each specific operating point with open -loop control mode by universal characteristic experiment .The general gasoline engine determines the actual operating condition according to the measured condition parameters .Furthermore , the oxygen-enriched intake emission of gasoline engine will be controlled by determining the intake oxygen volume fraction acquired in map .The load characteristic confirmatory experiments of HC , CO and NOx with two different intake ways of normal intake and oxygen-enriched intake are implemented under 2 000 r/min and 3 000 r/min, respectively .Validation results show that the HC and CO emissions decrease obviously under the oxygen -enriched intake compared with the normal intake , nevertheless, the NOx emission increases.The minimum value decrease rates of HC emission are 18.26%and 14.02%, and the minimum value decrease rates of CO emission are 17.78%and 16. 87%, moreover , the minimum growth rates of NO x emissions are 10.61%and 8.70%under the speed condition of 2 000 r/min and 3 000 r/min, respectively.