论文标题:内燃机配气系统的非线性动力学研究
Study on Nonlinear Dynamics of Valve System of Internal Combustion Engine
论文作者 王韬
论文导师 郝志勇,论文学位 博士,论文专业 动力机械及工程
论文单位 天津大学,点击次数 148,论文页数 129页File Size726k
2004-07-01论文网 http://www.lw23.com/lunwen_170675137/ 配气系统;气门弹簧;固有频率;多重共振;拉扭耦合振动;分岔;非线性振动;多尺度法
Valve system;Valve spring;Natural frequency;Multi-resonance;Extensional-torsional coupled vibration;Bifurcation,Nonlinear vibration;Method of multiple scales
本文的工作紧密联系工程实际,从现代内燃机设计的需要出发,推广和应用非线性振动理论和配气系统动力学分析方法,从理论和实验角度研究了配气系统由物理参数引起的多重共振特性,揭示了气门弹簧多重共振、拉压和扭转耦合振动与配气系统各种物理参数之间的关系。通过本文的工作,试图为内燃机配气系统的优化设计奠定一些研究基础。本文的研究内容和主要结果有以下几个方面:概述了配气系统的非线性动力学研究现状和研究方法,总结配气系统非线性动力学的研究进展。重点介绍了非线性振动理论的一些基本问题,包括常用求解方法,解的某些物理性质等。 以顶置凸轮轴配气系统为研究对象,利用振动力学理论着重分析连续模型与离散模型的运动学与动力学响应。本章给出了利用连续模型计算气门弹簧的动态响应和气门受力情况的理论方法,为配气系统的工程设计提供理论参考。讨论了初始条件对气门弹簧动力学特性的影响。利用离散模型建立了气门弹簧的运动微分方程组,并对并圈产生的碰撞力进行了详尽分析。在理论研究的基础上进行了仿真研究,与实测结果吻合。针对气门弹簧,首次研究了一阶固有频率与二阶固有频率之间满足 1:2 内共振关系时,气门弹簧的二重共振和三重共振,揭示了多重共振的规律。通过分析系统的分岔方程,求得了各种共振条件下的分岔响应,并获得了振动响应与激励幅值变化的关系。根据理论分析结果,指出气门弹簧的刚度和阻尼是影响气门弹簧振动分岔响应拓扑结构的主要物理参数,为气门弹簧振动的主动控制指明了方向。通过实验结果验证了两种二重共振理论分析结果的正确性,为配气系统多重共振理论分析方法进一步发展奠定基础。研究了气门弹簧拉扭耦合振动,揭示了由物理参数引起的纵振与扭振相互耦合振动的规律。这种耦合振动分析的观点,可以为全面探索配气系统的振动规律提供帮助。
This dissertationis based on the requirement of design of modern ICE and theconcrete engineering problems of valve system. Nonlinear vibration theory and themethod of dynamical analysis are applied and developed originally in the research ofnonlinear dynamics of valve system. Characteristics of multi-resonance of valvesystem resulted from physical parameters are investigated both in theory andexperiment. The relations between multi-resonance, longitudinal-torsionvibration andsome physical parameters are revealed. Through this dissertation, some fundamentalsare set up with the aim to optimize valve system design. The contents and major results of this dissertationare as follows: The condition and method of nonlinear dynamics of valve system are brieflyreviewed, and progresses in this field are concluded. Some basic aspects of nonlinearvibration theory, including solution method commonly used and some properties ofsolutions are emphasized. Investigating valve system with OHV, the kinematical and dynamical responseof continuous and discrete model are analyzed using vibration theory. The theoreticalmethod calculating dynamic response of valve spring and load on valve are presented,which is helpful for engineering design of valve system. The effect of initialconditions on dynamical Characteristics of valve spring is discussed. The differentialequations of motion of valve spring are set up using discrete model, and clash forcedue to neighboring coils contacting each other is analyzing in detail. On the basis ofthis computer simulation is conducted and coincidence is achieved. Nonlinear responses of double-resonance and triple-resonance of valve springare investigated with 1st order natural frequency to 2nd satisfying 1:2 internalresonance relationship. The study shows complicated laws of multi-resonance. Thedynamic bifurcation responses are analyzed under several different resonanceconditions, and the relationship between the response and the magnitude of excitationis exhibited. According to the theoretically analytical results, stiffness and damping ofvalve spring are principally physical parameters impacting the structure of bifurcationresponses, supplying a direction for vibration active control. The theoretical results oftwo kinds of double-resonance verified by experiment. A theoretical investigation of the coupled extensional-torsional vibration ofvalve spring is presented. The law between these two vibration mode coupling isrevealed. This concept of coupled vibration analysis is helpful to detecting vibratorylaws of valve system.
|
