小型通用四冲程汽油机循环波动特性研究

根据实测小型通用四冲程汽油机气缸压力，分析了最大爆发压力、最大爆发压力所对应曲轴转角、平均指示压力以及最大压力升高率等参数的循环波动特性，以及点火提前角、负荷和发动机转速对循环波动的影响。试验结果表明：在低速及小负荷工况下，循环波动率较大；在全负荷及标定转速下，循环波动率小。适当加大点火提前角，可使原机的稳定性变好。

Characteristics of cyclical variation for four-stroke small utility gasoline engine

According to the measured pressure data of the four-stroke small utility gasoline engine, the cyclical variations of the maximum pressure, the crank shaft angle at the maximum pressure, the mean indicated pressure and the largest pressure rise rate were analyzed. Meanwhile, the influences of ignition advance angle, load and rotation speed on cyclical variation were also investigated. The test results show that the coefficient of cyclical variation, at the lower rotation speed and lower load, is larger than that at the full load and rated speed. Moreover, the combustion stability of the engine can be improved when the ignition advance angle is increased properly.