液压自由活塞发动机电控压缩冲程机理与能量回收的基础研究

项目名称： 液压自由活塞发动机电控压缩冲程机理与能量回收的基础研究

项目编号： No.51505160

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 机械、仪表工业

项目作者： 任好玲

作者单位： 华侨大学

项目金额： 22万元

中文摘要： 液压自由活塞发动机（HFPE）具有可变压缩比，能根据工况使发动机处于最佳燃烧点或最低排放点。但在特定工况下，基于液压压缩装置的HFPE压缩比的精确控制较难保证，导致HFPE的工作不稳定。另外，膨胀冲程后期由于节流缓冲现象导致部分活塞组件的动能以热能形式损失掉，不利于能量的回收。针对HFPE压缩比的精确控制与能量回收问题，提出一种新型电动/发电机-机械传动机构耦合的动力驱动方案，以液压蓄能器与超级电容作为能量储存单元，建立燃烧腔压力-机械传动机构-电动/发电机-液压腔压力之间的多体动力学模型，研究电动/发电机的运行特性对压缩比和压缩过程稳定性的影响，分析电动/发电机与机械传动机构间的运动耦合方式及解耦控制，探讨压缩/膨胀过程中的能量流动和分配情况，研究液压能与电能存储的比例和相互转换对HFPE运动特性的影响，提出一种基于多能量存储方式转换的控制策略，为保证压缩比稳定和提高能量利用提供参考。

中文关键词： 液压自由活塞发动机；压缩冲程；液压混合；能量回收；能量管理

英文摘要： Hydraulic free piston engine can work at the best combustion or lowest emission condition due to its variable compression ratio. But in the certain condition, the accurate compression ratio is hard to keep when the compression process is driven by the hydraulic system. This leads hydraulic free piston engine work unsteadily. In addition, part of the kinematic energy of the free piston assembly in the expansion stroke is converted into heat because of the throttling action, which reduces the energy usage ratio and output of the system. Based on the aim to make the compression ratio stable and improve the energy usage, this project puts forward a new hydraulic free piston engine structure with motor/generator which couples with the gear-rack to drive the free piston assembly and achieves synchronous operation. This new structure introduces the hydraulic accumulator and super-capacitor to the energy saving system. Multi-body dynamic model including internal combustion engine, hydraulic system, gear and motor/generator is set up. The characteristics of the compression and expansion stroke of the proposed hydraulic free piston engine with the motor/generator controlled compression stroke are studied. The energy flow and energy distribution during the compression and expansion stroke are analyzed. The main parameters which influence the compression ratio and operation characteristics are discussed. Through monitoring the load condition, pressure of the compression accumulator, state of charge of the energy storage unit, the conversion conditions between the hydraulic energy and the electric energy are recognized and established. And a control strategy based on the working condition discrimination and multi-energy storage conversion is put forward to make the compression ration stable and improve the energy usage.

英文关键词： hydraulic free piston engine;compression stroke;hydraulic hybrid;energy recovery;energy management