增程器中发动机曲轴主轴承异常磨损问题研究

Research on Abnormal Wear of Crankshaft Main Bearing in Range-Extender Engine

针对增程器在耐久试验中出现的发动机主轴承(曲轴颈、轴瓦)异常磨损的问题,对增程器轴系进行了扭转振动和弯曲振动分析,发现增程器轴系在运转过程中有共振现象且共振节点位于发电机转子处。通过仿真设计增加了轴系中双质量飞轮的次级质量,结合增程器台架振动试验选出最优方案,并对优化后的增程器轴系进行了模态和主轴承EHD(Elastohydrodynamic,弹性流体动力学)分析,再对轴系改进后的增程器进行了1 000 h的台架耐久试验验证。结果表明:改进后的增程器轴系弯曲模态节点向飞轮处转移,振幅明显降低,曲轴主轴承所受力矩变小,轴心轨迹绕理论轴心基本对称分布,不再偏向一侧,飞轮振动加速度降低,且经过1 000 h试验后增程器的曲轴颈和轴瓦无明显磨损,该优化方案有效、可行。

The range-extender engine had abnormal wear of Crankshaft main bearing(crankshaft journal and bearing) during the endurance test. To explain this problem,the torsional vibration and bending vibration of range-extender Shafting were analyzed. It was found that there was resonance phenomenon in the operation of the range-extender’s Shafting,and the resonance node appeared around generator rotor. By simulating and designing,the weight was added to the secondary mass of the dual-mass flywheel,combing the vibration results of the range-extender in test bed,the optimum scheme was selected. Furthermore,the modal analysis of Shafting and the EHD(Elastohydrodynamic)analysis of the main bearing were carried out for optimized range-extender’s Shafting. After modifying shafting,the range-extender was tested for 1000 hours. The results show that the bending mode node of the optimized range-extender’s Shafting transfers from generator rotor to flywheel,the amplitude decreases obviously,the received moment of crankshaft main bearing becomes smaller,and the bearing center orbit is symmetrically distributed around the theory axis center,no longer biased to one side,the vibration acceleration of flywheel becomes smaller.In addition,crankshaft journal and bearing are found no obvious wear after 1000 hours endurance test. So the optimization solution is effective and feasible.