自由活塞极限位置的液压节流控制

Hydraulic Throttle Control for Free Piston Extreme Position

针对单活塞液压自由活塞发动机自由活塞运动不受机械机构约束的情况,研究单活塞液压自由活塞发动机自由活塞极限位置的液压节流控制方法,保证系统机械结构安全。基于对自由活塞极限位置节流控制原理的分析,建立液压控制回路数学模型,结合试验和仿真分析节流控制的工作特征及其影响因素。研究结果表明,单活塞液压自由活塞发动机极限位置的液压节流控制应考虑单向阀节流、回油阻尼和油液弹性三种作用效果的影响。压缩腔压力在膨胀冲程的第一次压力峰值由单向阀引起,第二次压力峰值由回油阻尼和油液弹性引起。增大回油孔通流面积可减小第一次压力峰值压力波后期高压的持续时间。回油阻尼和油液弹性能有效防止单活塞液压自由活塞发动机机械损坏的发生。

The free piston motion of a single piston hydraulic free-piston engine is not restricted by any mechanical linkages.To protect the mechanical structure from damaging,a hydraulic throttle control method for free piston extreme position of the single piston hydraulic free-piston engine is investigated.The fundamentals of the hydraulic throttle control method for free piston extreme position are analyzed.The mathematic model of the hydraulic control circuit has been built up.The working characteristics and the contributed factors of the throttle control method are analyzed based on experiments and simulations.The results indicate that the throttle effect of the check valve,the dump port throttle and the oil bulk modulus should be considered in the throttle control method for free piston extreme position of the single piston hydraulic free-piston engine.The first pressure peak in the compress chamber of expansion stroke is caused by the check valve.The second pressure peak is caused by the dump port throttle and the oil bulk modulus.The duration of the high pressure wave after the first pressure peak is reduced by increasing the dump port flow area.The damage of the free piston and the engine body is effetely prevented by the dump port throttle and the oil bulk modulus.