汽油机怠速工况曲轴滚振特性的试验研究

建立了四缸汽油发动机的怠速闭环控制系统及曲轴滚振测试系统,在650r/min、800r/min、1000r/min三种怠速工况下,对反映发动机怠速稳定性的曲轴滚振特性进行了试验研究。对滚振幅频特性及相频特性的分析结果表明,在发动机连续工作50个循环内,三种怠速工况下0.5谐次滚振的平均幅值最大且存在着较大的循环波动,2.0谐次的次之,1.0谐次和1.5谐次的相对较低。0.5谐次的滚振及其循环波动是由于发动机各缸燃烧压力的差异以及缸内燃烧压力的循环波动引起的。随怠速转速的增大,0.5谐次和2.0谐次滚振的平均幅度及其循环波动幅度明显减小。当怠速不同时,由于各缸燃烧压力差异的变化,0.5谐次滚振的相位也随之变化。

Experimental Study on Rolling Vibration Characteristic of Gasoline Engine Crankshaft at Idle Condition

The idle closed -loop control system Four- cylinder gasoline engine and the crank- shaft rolling vibration test system were established. The crankshaft rolling vibration characteristic which indicates the idle stability of the engine was experimentally investigated at 650 r/min, 800 r/ min and 1000 r/min, respectively. The amplitude- frequency characteristics and the phase- frequency characteristics of rolling vibration within 50 continuous cycles of the engine show that the average amplitude of 0.5 order vibration is the largest and there are large fluctuations in these cycles, and that of 2.0 order is the second, and that of 1.0 order and 1.5 order are relatively low. The 0. 5 order vibration and its cycle fluctuation results from the difference of combustion pressure of each cylinder and its cycle fluctuation. When the idle speed increases, both the average amplitude and the cyclic fluctuation amplitude of 0.5 order and 2.0 order rolling vibration reduce significantly. When the idle speed changes, the difference of combustion pressure of each cylinder is variable, and the phase of 0.5 order rolling vibration changes as well.