【作者】 周盛；

【导师】 杨华勇； 徐兵；

【作者基本信息】 浙江大学 ， 机械电子工程， 2006， 博士

【摘要】 液压自由活塞发动机(Hydraulic Free Piston Engine，以下简称HFPE)是近30年逐渐发展起来的新型动力装置，它是将内燃机和液压泵集成为一体，以液体为工作介质，利用油液的压力能，实现动力非刚性传输的特种发动机。在HFPE中活塞组件是由内燃机活塞与液压泵活塞通过活塞杆直接刚性连接而成。和传统发动机／液压泵的组合动力相比，它省去了曲轴式内燃机中将活塞往复运动转换为旋转运动的曲柄连杆机构，以及液压泵中将旋转运动转换为泵活塞往复运动的旋转斜盘机构。因此具有结构简单、零件数少、重量轻、成本低、效率高、燃料适用性好及易于回收系统频繁启停中惯性能和重力势能等优点。 本论文以双活塞式液压自由活塞发动机(Dual Piston HFPE，以下简称DHFPE)及其关键部件作为研究对象。在国家“863”高技术发展计划项目和国家自然科学基金项目共同资助下，试制成功第一代DHFPE原理样机。通过对DHFPE的试验与仿真研究，提出DHFPE的工作频率与工质压缩比间存在单调递增的函数关系，并且DHFPE系统是大范围稳定系统。 针对第一代样机中存在的不足之处，开展了第二代样机的研制工作。目前已经研制成功第二代DHFPE的关键部件——数字阀和增压式燃油喷射系统。采用试验与仿真相结合的方法对数字阀阀芯优化设计开展了系统地研究。针对球阀、锥阀和滑阀三种数字阀阀芯，提出不同的液动力补偿方案，并给出阀芯设计参数与液动力的关系曲线。当阀口压差较大时，传统阀口射流流场仿真模型的计算误差较大，鉴于这种状况，提出阀口紊流射流经验数值仿真模型。该模型能考虑气穴现象对液流物理性能的影响，从而提高了阀口流场的计算精度。根据DHFPE的特点确定其燃油系统采用增压式燃油喷射系统。对增压式燃油系统中的压力冲击现象和燃油喷射可控性进行了试验研究，为DHFPE控制系统研制提供了试验依据。 本论文的主要内容可分为6章，现分述如下： 第1章，阐述了HFPE研究背景以及国内外研究现状，论述了DHFPE系统需要解决的关键技术问题，提出了本课题的研究内容。 第2章，依据第一代DHFPE样机的实际参数建立了仿真模型，仿真结论与实验数据吻合良好。在仿真和试验数据的基础上分析了DHFPE与传统发动机在运动和燃烧特性上的差异，以及DHFPE设计参数与系统整体性能指标间的耦合关系。最后运用相轨迹法研究了DHFPE的运动特性，并提出DHFPE稳定运行的必要条件。在简化线性运动模型基础上研究了DHFPE的幅频特性， 第3章，阀芯液动力补偿是数字阀设计中的一个关键环节。针对不同类型的数字阀，提出了不同的液动力补偿方法。滑阀阀芯设计中提出了缝隙滑阀结构，以减小阀芯的稳态液动力和瞬态液动力；球阀数字阀采用二次节流技术，减小阀芯运动阻力；锥阀阀芯设计采用阻尼套压力补偿法，该方法能实现稳态液动力的欠补偿或过补偿。最后对阀口更多还原

【Abstract】 This doctoral thesis comes from the project "Free Piston Engine Hydraulic Reciprocating Pump" supported by the National High Technology Research and Development Program ("863" Program, the project serial number is 2001 AA423150) and the project "Study on the Mechanism of Hydraulic Free Piston Internal Combustion Engine" (the project serial number 50075077) supported by National Science Foundation of china (NSFC).A hydraulic free piston engine (abbreviated as HFPE) integrates internal combustion engine and a hydraulic pump into one compact unit. In practical view, there is only one linearly moving part, i.e. the piston assemble in the HFPE. Comparing with crankshaft internal combustion engine , the piston assemble within HFPE is not restricted by any mechanical linkages, so its forth between left and right extremes by means of the fuel energy, simultaneously its hydraulic piston directly produce hydraulic energy.Comparing with the single piston or opposed piston HFPE, the dual piston HFPE (abbreviated as DHFPE) has its own special features such as the highest power density, so the aim of this thesis is to study the mechanism of DHFPE and its key component. The main content of this thesis could fall into five chapters as the followings.Chapter 1 the history and current research status of HFPE are introduced based on a lot of the publications and conference papers. The key techniques of HFPE are also described. Consequently, the goal of research and project are brought forward.Chapter 2 study on the mechanism of the DHFPE. The mathematical models of every subsystem included in the DHFPE have been built up and verified by experiment data. Based on simulation result of DHFPE, DHFPE structure parameters optimization were developed. Then the performance and stability of DHFPE was analyzed. The motion of DHFPE is self-sustained oscillation with variable rigidity and variable damp. According to DHFPE amplitude frequency characteristics, the necessary condition of DHFPE stable operation was presented.Chapter 3 discusses the design of digital valve spool. A new slid valve has been developed. The valve, named "slot valve" because of its slop-spool shape, make it possible to keep flow force in low level. A new method was presented to reduce flow force of diverged flow cone valve, the damping ring method. First an experiment device was designed that used for measuring flow force without friction influence. Then spool flow force with various design parameters was measured by the experiment device. Final the relationship between cone valve design parameter and flow force is presented. At the end of this chapter, a new k-更多还原