以中高转速区性能为目标的单缸柴油机配气凸轮优化

Valve Cam Optimization of Single Cylinder Diesel Engine with the Goal of the Performance at Medium and High Speed

使用AVL BOOST建立186FA柴油机的仿真模型,通过模拟计算得到速度特性下配气相位对样机工作性能的影响,分析表明配气正时对不同转速下柴油机性能的影响存在差异,进气迟闭角对高转速区的性能影响较显著,排气提前角对泵气损失影响最大,进气提前角主要影响高转速区的充量系数,而排气迟闭角对低转速区的充量系数影响显著。以柴油机中高转速区的性能为主要目标,对配气相位进行优化,并将优化后的配气相位用于凸轮型线的设计中。使用优化后的配气凸轮进行试验,结果显示,在速度特性曲线上相同功率时,优化后的配气凸轮可提高柴油机在中高转速区的经济性,其中标定工况下比油耗减少了4.66g/(k Wh),降低了约1.68%,充量系数由0.82增加到0.84,升高了2.44%。

The simulation model of 186FA diesel engine was established by AVL BOOST and the valve timing＇s influences on the performance of this engine under speed characteristic were got through the simulation calculation. According to the analysis, these influences are different at different speeds. The intake valve close angle has a comparatively obvious impact on the performance at high speed while the exhaust valve open angle has the biggest impact on the pumping losses. The intake valve open angle mainly affects the volumetric efficiency at high speed, while the exhaust valve close angle is on the opposite. The valve timing was optimized with the aim of the performance at medium and high speed and then was applied to the design of the cam profile. Through the test of the optimized valve cam, the result＇showed that it can enhance the economical efficiency of the engine under the same power at medium and high speed which means the fuel consumption reduced by 4.66g/ （kWh） at decreasing by about 1.68% and the volumetric efficiency grew from 0.82 to 0.84, increasing by 2.44% compared with the original valve cam.