摘要
为精确描述配气机构中气门弹簧的非线性刚度特性和动态颤振现象,提出一种整体式气门弹簧的几何非线性动力学模型,通过添加接触力元建立配气机构刚柔耦合动力学模型,结合气门弹簧的螺旋结构和大变形特点,选取弹簧半径、弹簧高度、螺旋线极角、簧丝截面扭转角以及在弹簧两端节点处对初始极角的一阶导数作为气门弹簧的描述变量,在弹簧单元域内采用三次样条插值离散;基于Bernoulli梁假设的几何精确梁理论,建立含轴向应变和曲率矢量的弹簧变形虚功率,在数值求解中滤除柔性弹簧模型中的应力高频振荡分量,实现ODE45常规微分求解器的快速求解.计算结果表明:气门弹簧在静态压缩过程中具有明显的非线性刚度变化,与传统模型相比偏差不大于2.4%;配气机构的转速越高,气门弹簧动态力颤振现象就越明显;在正常工况下配气机构的接触受力情况与集中质量弹簧模型计算结果相吻合.
In order to investigate the nonlinear stiffness characteristic and the spring surge of the valve spring,a geometric nonlinear dynamic model of the whole valve spring was presented,and the rigid-flexible coupling dynamics model of the valve train was established by adding the continuous contact forces.Combined with the spiral structure of valve spring and the characteristics of large deformation,the spring radius,spring height,spiral pole angle,torsion angle of wire section and the first derivative with respect to the initial polar angle at the ends of the spring were selected as the description variables of the valve spring.Cubic spline interpolation was used in the spring element.Based on the geometrical exact beam theory with the Bernoulli beam hypothesis,the spring deformation virtual power equation was described with axial strain and curvature vector.In order that the equations could be solved quickly by regular ordinary differential(ODE45)solvers,the method of filtering high frequency vibrations of the stress in the flexible spring during the process of modeling was applied.As validated by the numerical examples,the valve spring model has obvious nonlinear stiffness change in the static compression process,and the error is no more than 2.4%compared with the traditional model.The faster the speed of valve train is,the more obvious the surge phenomenon of valve spring dynamic force is.Under normal working conditions,the contact forces of valve train are consistent with the result of the lumped mass model of spring.
作者
张健
齐朝晖
卓英鹏
徐金帅
Zhang Jian;Qi Zhaohui;Zhuo Yingpeng;Xu Jinshuai(State Key Laboratory of Structural Analysis for Industrial Equipment,Dalian University of Technology,Dalian 116023,China)
出处
《内燃机学报》
EI
CAS
CSCD
北大核心
2021年第3期279-287,共9页
Transactions of Csice
基金
国家自然科学基金资助项目(11872137,91748203).
