摘要
曲轴的非刚体特性决定了扭转振动是不可避免,在设计中必须要加以考虑的因素。针对某四缸发动机扭转振动特性进行分析,采用集中质量法对曲轴轴系进行扭转振动建模,获取系统的特征方程,分别应用并对比了二自由度和六自由度当量系统方法,获取轴系的自振频率和振型,并获取低谐次的共振转速;采用非接触式试验测试,对比曲轴系统试验数据和理论分析数据,获得校准后的发动机轴系扭振计算模型,对比了两种求解模型结果的差异性,并对理论计算结果进行修正。结果可知:二自由度和六自由度当量系统法均可对曲轴轴系的自由振动特性进行分析,二者的误差在4%以内;在发动机的转速范围内,对于该发动机轴系的主谐次和次主谐次,存在多个共振转速,需要设计专门的扭转减振器进行控制;基于扭转振动实验测试,对曲轴轴系的扭转振动模型进行修正,可以显著提高二自由度和六自由度当量系统法获得的轴系自由振动特性的准确性,二者的误差控制在0.5%以内;同时模型分析与试验测试结果基本一致,表明分析模型的可靠性,为实际设计提供重要参考。
The non-rigid characteristics of the engine crankshaft determine that the torsional vibration is unavoidable and must be considered in the design.Aiming at the torsional vibration characteristics of a four-cylinder engine,the torsional vibration of the crankshaft shafting was modeled based on the lumped mass method,and the characteristic equations of the system were obtained.The two-degree-of-freedom and six-degree-of-freedom equivalent system methods were applied and compared to obtain the shafting system.The natural frequency and mode shape of the shafting were analyzed,and Low harmonic resonance speed was analyzed.The non-contact test was used,and the crankshaft system test data and theoretical analysis data were compared.The engine shaft torsional vibration calculation model was corrected.The differences between the two models for solving the model were compared,and the theoretical calculation results were corrected.The results show that the two-degree-of-freedom and six-degreeof-freedom equivalent system method can analyze the free vibration characteristics of the crankshaft shafting,and the error between them is less than 4%.Within the engine speed range,for the primary and secondary main harmonics of the engine shafting,there are multiple resonant speeds that are controlled by the specialized torsional vibration damper;based on the torsional vibration experimental test,the torsional vibration model of the crankshaft shaft system is corrected,which can significantly improve the two degrees of freedom and the six freedoms.The accuracy of the free vibration characteristics of the shafting obtained by the degree equivalent system method is controlled within 0.5%.At the same time,the model analysis is basically consistent with the experimental test results,indicating the reliability of the analytical model and providing an important reference for the actual design.
作者
刘义付
孙瑞霞
LIU Yi-fu;SUN Rui-xia(Huanghe Jiaotong University,He’nan Jiaozuo 454000,China)
出处
《机械设计与制造》
北大核心
2021年第8期211-215,共5页
Machinery Design & Manufacture
基金
河南省焦作科技计划项目(180113)。
关键词
发动机
曲轴轴系
扭转振动
固有特性
集中质量法
试验
Engine
Crankshaft
Torsional Vibration
Inherent Characteristics
Centralized Mass Method
Test
