液压自由活塞发动机止点位置控制研究

研究液压自由活塞发动机活塞运动止点控制方法,进而提高系统运行的稳定性。对单活塞液压自由活塞发动机活塞位置控制基本原理进行了理论分析,研究了活塞止点控制的影响因素。基于仿真和试验结果,确定了上止点精确控制主要控制量,分析了下止点精确控制策略及其极限位置限制方法。研究结果表明,上止点精确控制主要影响因素为活塞压缩过程的初始运动位置和初始压缩位置,下止点精确控制策略需要同时控制活塞所传递的能量以及活塞下止点附近的动力学过程。活塞下止点极限位置应采用组合方法限制,前期基于液压节流作用的热能法,后期基于液压油体积弹性模量的势能法。

Dead Center Control of Hydraulic Free-Piston Engines

To increase the operation stability of a single piston hydraulic free-piston engine, the deadcenter control methods of the piston are analyzed. The fundamentals of the piston position control of thesingle piston hydraulic free-piston engine are investigated theoretically. The contributing factors of thedead center control are analyzed. Based on the simulation and experimental results, the factors of the topdead center (TDC) accurate control, the control strategy for the bottom dead center (BDC) accuratecontrol and its terminal position limit methods are investigated. The results indicate that the main contrib-uting factors of TDC control are the stroke and the initial compression position of the compression stroke.The transferred energy and the dynamics process around BDC of the piston need to be considered in theBDC accurate control strategy. A combinatorial method, i. e. the combination of the heat energy methodbased on the hydraulic throttle effect and the potential energy method based on the hydraulic fuel bulkelastic modulus, is given for the BDC limiting position control.