两种米勒循环方案对发动机性能影响对比

摘要

应用通过提早或迟后关闭进气门的米勒循环降低缸内最高燃烧温度以达到降低缸内NOx排放目的.基于GT?power软件建立并校准TBD620单缸机的仿真模型,对变气阀重叠角(VVO)和变凸轮型线(VCT)两种米勒循环方案进行仿真分析,对比了二者对TBD620单缸机经济性能及NOx排放的影响.结果表明,两种方案,米勒度越大,低负荷工况油耗越少,高负荷工况油耗先减少后增大;NOx排放明显减少,高负荷时降幅为90%以上.与VCT方案相比,VVO方案的经济性能和排放性能较优.%By applying Miller cycle in which the intake valve is closed ahead of time or later, the maximum combus-tion temperature in the cylinder wass lowered for the purpose of reducing the emission of NOx from the cylinder. A simulative model on TBD620 single-cylinder engine was established and calibrated on basis of GT-power software, then a simulative analysis was made for the vary valve overlap ( VVO) and vary cam Timing( VCT) scheme, the effects of both schemes on the economy of TBD620 single-cylinder engine and NOx emission were compared. The re-sults show that, for both VVO and VCT, with the increase of Miller timing, the fuel consumption decreases under the condition of low load, while for the condition of high load, the fuel consumption decreases first and then increa-ses;NOx emission decreases significantly, and the decrease range is more than 90% at high load. Compared with VCT, VVO has better economy and emission performances.