双燃料发动机气缸压力变动研究

为了准确测量发动机气缸压力、分析燃烧过程,开发了一套可同时测量多缸汽油机各缸示功图的高速数据采集系统,最多同时采集16路信号,最大采样频率1MHz.应用本数据采集系统对化油器发动机改造的双燃料发动机进行了测试.每个气缸测量了至少50循环的压力数据,用倒拖最大压力的平均值为评价标准比较了各缸的进气量差异.同时,分别连续测量了各个气缸燃烧汽油和CNG时的燃烧压力.最后,用最大燃烧压力的平均值和变动系数比较了各缸的燃烧变动.实验结果表明,实验用发动机的各缸进气和燃烧状况存在明显差异,而燃用CNG时最大燃烧压力的变动系数小于燃用汽油时的数据.

Study on the Cylinder Pressure Fluctuate for a Double Fuel S.I. Engine

A high-speed data acquisition system for multi-cylinder spark ignition engine was developed in order to measure the indicator diagrams of each cylinder simultaneously with the maximum sampling frequency of 1 MHz and the total input signals of 16 channels at the same time. A carburetor S. I. engine reconstructed into a double fuel engine has been tested using the data acquisition system in this research. At lease 50 cycles' pressure data of each cylinder were measured. The average value and the fluctuant coefficient of maximum pressure were calculated. The comparison a-mong different cylinder's inlet air quantity has been made using the maximum pressure's average value. Then the combustion pressures of each cylinder have been measured continuously and simultaneously on condition that either burning gasoline or compressed natural gas (CNG). The comparison of combustion and variation among each cylinder has been made using the averaged value and the variation coefficient of the maximum combustion pressure. The experiment results show that the variation coefficient of the maximum combuction prossure when burning CNG is lower than the value of gasoline engine.