直列四缸发动机曲轴扭转振动固有特性分析

Natural Characteristics Analysis of Crankshaft Torsional Vibration of In-Line Four-Cylinder Engine

准确分析发动机曲轴扭转固有特性是曲轴扭振减振器设计的基础,以某四缸汽油发动机曲轴轴系为研究对象,分别用基于有限元模型和集总参数模型模态分析法计算曲轴轴系扭转固有特性。对建立曲轴轴系有限元模型方法,特别是活塞连杆机构的几种等效方法及集总参数模型中曲轴各段扭转刚度有限元全模型计算方法进行分析;对不同方法获得固有特性进行对比。结果表明:基于连杆轴颈中央截面分段直接刚度计算法和基于连杆轴颈和主轴颈中央截面分段然后串联间接法两种途径计算的曲轴各段扭转刚度一致性好,精度满足工程要求;基于集总参数模型与有限元模型的扭转固有特性分析结果一致,这两种方法是统一的,可直接应用于工程分析或研究工作。

Accurate analysis of the torsional natural characteristics of the engine crankshaft is the basis for the torsional vibration damper design. Taking an in-line four-cylinder gasoline engine crankshaft as example,the crankshaft shafting torsional natural characteristics was analyzed based on modal analysis method of finite element model and lumped parameter model. The method for establishing finite element model of the crank shaft,especially several equivalent method piston rod mechanisms was analyzed. Crankshaft torsional rigidity of each segment of finite element method full model in lumped parameter model was analyzed. The natural characteristics of different methods were compared. The results show that：Crankshaft torsional stiffness paragraphs consistency,precision engineering to meet the requirements,which through rigidity calculation method based on direct central rod journal sectional segments and based on the central main journal and rod journal sectional segment then series two ways to calculate the indirect method. The natural characteristics of reverse lumped parameter model and finite element model results are in agreement. These two methods are unified and can be directly applied engineering analysis or research.