液压自由活塞发动机的活塞运动不对称特征研究

Study on the Asymmetry Characteristics of Piston Motion of the Hydraulic Free Piston Engine

结合液压自由活塞发动机基本原理,建立了系统分析模型,通过仿真和样机试验结果分析了活塞运动不对称性及其影响因素。研究结果表明:液压自由活塞发动机活塞上止点运动呈现不对称性特征,能量传递特征和活塞受力特征决定了该不对称性是固有的。在上止点附近,气体压力对活塞运动状态起决定性作用,活塞压缩过程越快,对应的膨胀过程也越快。配流阀响应对活塞上止点运动状态影响不明显,不同负载压力形成位置主要影响膨胀过程后期。

Based on the hydraulic free piston engine fundamental theory, the analytical model of the sys- tem was built. The asymmetry of the piston motion and the influencing factors were investigated by simu- lation and prototype tests. The results indicate that the piston motion around top dead center of the single piston hydraulic free piston engine appears asymmetry. The energy transfer characteristics and the forces on the piston around top dead center determined that the asymmetry characteristic is inherent. The piston motion around top dead center is mainly determined by the cylinder gas pressure. The faster the compres- sion procession is, the faster the expansion process is. The responses of the distributing valves affect the piston motion around top dead center little. The operation position of the load pressure mainly affects the end of the expansion process.