【作者】 杨东亚；

【导师】 龚俊；

【作者基本信息】 兰州理工大学 ， 机械制造及其自动化， 2013， 博士

【摘要】 斯特林发动机闭式回热循环的工作特性要求活塞杆密封装置必须具有可靠的密封性能。活塞杆Leningrader密封性能具体表现为泄漏量、使用寿命与摩擦功耗,而根据密封原理可知,密封摩擦副的摩擦学行为是决定其密封性能的关键。所以,本文以密封摩擦副的弹流润滑特性研究为切入点,揭示关键工况与结构因素及密封件的粗糙度对Leningrader密封性能的作用机理与影响规律,构建斯特林发动机活塞杆密封基础理论,为密封装置的创新设计和密封结构的优化设计提供科学依据与理论指导。本文按照递进关系及理论研究与实验验证相结合的研究方案,首先进行系统工况因素对Leningrader密封性能的影响研究,由定量研究到动态研究；在此基础上,再研究扩撑、过盈与磨损三个关键结构因素对Leningrader密封性能的作用机理与影响规律；基于工况与结构因素对密封性能影响的研究结论,创建混合润滑状态下考虑密封件表面粗糙度影响的活塞杆滑动密封性能分析数学模型,揭示粗糙度对密封性能的作用机理及其与其它因素共同作用的影响规律；最后,进行Leningrader结构润滑特性实验与密封性能实验,再通过数值比对与综合分析,确定Leningrader密封性能设计的关键参数及其规划策略。1)对Leningrader密封结构进行了简化、建模,在工况参数定量条件下研究了密封摩擦副的润滑特性,在此基础上,解析了润滑油压对摩擦副摩擦学行为的影响规律,再结合工程实际,重点研究了热效应、变速及挤压应力对Leningrader密封性能的动态影响,揭示了关键工况因素对密封性能的作用机理与影响规律。2)构建了Leningrader密封原理数学模型,研究了撑环扩撑作用下密封入口区“喇叭口”的弹性力学特性,基于EHD理论,解析了扩撑与过盈对Leningrader密封摩擦副弹流润滑特性的影响机制,再结合密封件的摩擦磨损性能,揭示了磨损对Leningrader密封性能的作用机理与影响规律。3)基于关键工况与结构因素对Leningrader密封性能影响的研究结论,创建了混合润滑状态下包括表面粗糙度影响的活塞杆滑动密封性能分析数学模型,综合流体动力学、变形力学与接触力学,研究了密封区混合润滑状态的形成机理,解析了密封表面粗糙度对密封性能的作用机理,揭示了粗糙度与系统结构及工况参数之间的匹配关系及相互作用规律。4)针对理论研究的实验验证问题,研制了机械结构上实现全封闭、数据检测上实现微流量测量的往复式活塞杆密封性能试验机,进行了Leningrader结构润滑特性与密封性能两种状态下的实验验证,完成了数值比对与综合分析,确定了活塞杆Leningrader密封性能设计的关键。总之,系统工况与结构参数的优化配置是进一步提升Leningrader密封性能的关键。性能设计的主要参数有速度、润滑油压、过盈量、加工精度、扩撑量与弹性模量,基本配置策略是在保证弹性模量稍小的密封件表面粗糙度的基础上,适当增大配合过盈量,在保证理想“喇叭口”形状的前提下,增大润滑油压,在系统热平衡的条件下,加大杆速。更多还原

【Abstract】 The high-performance of piston rod sealing device ensures the closed type regenerative cycle in Stirling engine. The sealing property of Leningrader seal embodies leakage rate, working life and friction power consumption. According to the sealing principle of Leningrader seal, it is obvious that the tribological behavior of friction pair is the root of the problem. So, based on the research on the elastohydrodynamic lubrication characteristics of friction pair, to explore and analyse the mechanism and influence law of key condition or structure factors and roughness in Leningrader seal, so as to build the basic sealing theory for Stirling engine piston-rod, and provide scientific proof for the innovative design of the sealing device and theoretical guidance for the optimization design of the sealing structure.In this dissertation, according to the gradual, layers of in-depth and theoretical studies combined with experiment research plan, the impact in sealing performance of the key condition factors in the Leningrader system is resaerched firstly. Then, on the basis of the reasearch of key condition factors, the action mechanism and influence laws of the key structural factors of Leningrader seal are studied. And then, based on the foregoing research conclusions, the numerical model of reciprocating rod seal including surface roughness and mixed lubrication is built, thus the action mechanism and influence laws of roughness combined with other key factors are explored. Finally, two experiments of lubricating property and sealing performance for the Leningrader seal are tested, and through the numerical comparison and comprehensive analysis, the key design parameters and their planning strategy for Leningrader seal are determined.1) A simplified model for Leningrader seal is built, and under the precondition of quantitative condition parameters, the lubrication characteristics of core sealing area is studied firstly. Then, bsed on the quantitative study, the action mechanism of lubrication pressure for friction pair lubrication properties is researched. Finally, combining with the engineering practice, the action mechanism and influence laws of heating effect, varying velocity and crushing stress in Leningrader sealing system are explored.2) The mathematical model of Leningrader sealing principle is built, and the elastic mechanical properties of sealing element under the action of expansion ring is researched firstly. Then, based on EHD theory, the influencing mechanism of the expansion and interference for the elastohydrodynamic characteristics of the Leningrader sealing area is studied. And finally, the action mechanism and influence laws of the wear are explored.3) Based on the research conclusions of working condition and structure factors, a numerical model of reciprocating rod seal including surface roughness and mixed lubrication is built. The model consists of three coupled ananlysis of fluid mechamics, deformation and contact mechamics. And then the formation mechanism of mixed lubrication state in sealing area is analysed, the action mechanism of roughness for sealing property is explored, and the interactional laws and matching relation between roughness and the system structure or the working condition factors are announced.Basically, the optimal allocation of system working condition and structure parameters is the key point to promote Leningrader sealing performance. The key parameters are velocity of the rod, lubrication pressure, magnitude of interference, machining precision, amount of expansion and elasticity modulus. The basic allocation strategy of these parameters is, on the basis of high surface quality of smaller elastic modulus sealing element, increasing the assembling interference; on the premise of ideal entrance shape of sealing core, strengthening the lubricating oil pressure; and under the condition of thermal equilibrium in the system, improving the shaft speed.更多还原