发动机曲轴与正时系耦合动力学研究

为了研究发动机曲轴与正时系的耦合作用,建立曲轴的多弹性体动力学模型,得到了曲轴的扭转振动、曲柄臂圆角的动态应力以及主轴承的弹性流体动力学结果.单独建立了正时系的多体动力学模型,分析了同步带内力及带与各带轮的啮合力.通过联合仿真的方法将曲轴与正时系耦合起来,考虑曲轴正时带轮的力、力矩以及位移的相互作用,得到了曲轴与正时系的耦合动力学结果.结果表明：耦合作用下的曲轴扭振幅略有增加,第一主轴承所受弯矩的变化增加了最大油膜压力以及减小了最小油膜厚度,第一曲柄臂圆角最大应力增加了39%,而正时系动力学受曲轴的影响较小.曲轴扭振实验验证了耦合模型更符合发动机的实际工况.

Study of coupling dynamics between crankshaft and timing drive system of engine

A multi-elastic body dynamic model of crankshaft was established to investigate the coupling effect between crankshaft and timing drive system of engine. The crankshaft torsional vibration, dynamic stress in fillet of crank web and elastic hydrodynamic (EHD) results of main bearing were obtained. A multi-body dynamic model of timing drive system was established separately to analyze the synchronous belt internal force and mesh force between belt and pulleys. The crankshaft and the timing drive system were coupled by co-simulation to consider the interaction of force, moment and displacement of the timing pulley. And then the coupling dynamic results between crankshaft and timing drive system were obtained. Results show that the crankshaft torsional vibration amplitude increases slightly with the coupling effect, the maximum oil film pressure increases while the minimum oil film thickness decreases with the first main bearing bending moment variation, and the maximum dynamic stress in fillet of first crank web increases by 3.9%. However, the dynamic of timing drive system is little influenced by the crankshaft. Torsional vibration test validated that the coupling model is more consistent with the actual engine working conditions than the uncoupling model.