发动机正时链系统动力学仿真分析

发布时间：2018-03-23 11:19

本文选题：正时齿形链　切入点：多体动力学　出处：《上海交通大学》2015年硕士论文

【摘要】：齿形链因其结构紧凑、传递功率高、可靠性与耐磨性能好,正成为发动机正时机构主流解决方案。然而随着发动机技术的发展,齿形链张力随着驱动负载不断增加而加大,链条张力是满足其与发动机全寿命的关键因素,但因链系统轨迹的不规则性,通过应变方法测量昂贵、可靠性差和耗时长等因素制约了国产齿形链的应用。本文基于Matlab建立正时链系统仿真模型,通过对比实验和仿真模型张紧器的动态特性验证仿真模型的正确性,再通过仿真模型计算的方法得到链条张力。首先,建立链系统几何模型。基于正时齿形链系统总体设计方法,对某双顶置凸轮轴发动机链系统进行布局设计,其各零部件经过简化后,利用布局设计得到几何位置,在Matlab实现几何建模。其次,建立链系统动力学模型及其求解程序。运用多体动力学理论,分析正时链系统各零部件的动力学模型,并首次引入曲轴扭振运动学模型及齿形链弹性动力学模型,使得正时系统动力学模型更接近实际工况；采用现代接触动力学原理,设计正时系统接触搜索策略及建立接触力算法模型；基于龙格-库塔数值积分方法设计仿真动力学求解程序。最后,分别通过求解仿真模型和实验方法得到张紧器活塞的运动量和活塞受力,通过对比验证虚拟仿真样机。利用该仿真模型研究不同张紧器泄漏量下,链条张力和活塞运动量的变化,为正确选择张紧器泄漏量提供指导。本文通过实验和仿真相结合的方法求解链条张力,仿真模型首次考虑曲轴扭振和齿形链弹性变形,并实验验证仿真模型可真实反映发动机实际工况,为国产齿形链在发动机正时系统的应用提供切实可行方法。
[Abstract]:Because of its compact structure, high transmission power, good reliability and wear resistance, toothed chain is becoming the mainstream solution of timing mechanism of engine. However, with the development of engine technology, the tension of tooth chain increases with the increasing of driving load. Chain tension is the key factor to satisfy the whole life of the engine, but because of the irregularity of the chain system trajectory, it is expensive to measure by strain method. The application of domestic toothed chain is restricted by the factors of poor reliability and long time consuming. In this paper, the simulation model of timing chain system is established based on Matlab, and the correctness of the simulation model is verified by comparing the dynamic characteristics of the model tensioner with that of the simulation model. Then the chain tension is obtained by the method of simulation model calculation. Firstly, the geometric model of chain system is established. Based on the overall design method of timing gear chain system, the layout design of a double-top camshaft engine chain system is carried out. After simplifying the parts, the geometric position is obtained by the layout design, and the geometric modeling is realized in Matlab. Secondly, the chain system dynamics model and its solving program are established, and the multi-body dynamics theory is used. This paper analyzes the dynamic model of each part of timing chain system, and introduces the kinematics model of torsional vibration of crankshaft and the elastic dynamic model of tooth chain for the first time, which makes the dynamic model of timing system more close to the actual working condition. Design contact search strategy and establish contact force algorithm model of timing system, design simulation dynamic solution program based on Runge-Kutta numerical integration method. The motion of the tensioner piston and the piston force are obtained by solving the simulation model and the experimental method respectively. The virtual simulation prototype is compared and verified. The simulation model is used to study the leakage rate of different tensioners. The variation of chain tension and piston movement provides guidance for the correct selection of tensioner leakage. In this paper, the chain tension is solved by the combination of experiment and simulation. The torsional vibration of crankshaft and elastic deformation of tooth chain are considered in the simulation model for the first time. The simulation model can truly reflect the actual working conditions of the engine and provide a feasible method for the application of domestic toothed chain in the engine timing system.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TK403

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