液压自由活塞发动机活塞运动规律动态仿真研究

Research on Piston Movement Dynamical Simulation of Hydraulic Free Piston Engine

为研究液压自由活塞发动机(HFPE)的活塞运动特性,建立了液压自由活塞发动机动态仿真模型,针对循环供油量、喷油定时、气门正时、压缩压力、负载压力等主要控制变量对活塞运动情况的影响进行了规律性研究。结果表明:各控制变量的变化影响活塞受力的变化,进而使活塞的下止点位置和压缩比发生变化,并影响发动机的正常运转和性能;循环油量与活塞膨胀行程长度、压缩能量与压缩比均近似呈线性关系;HFPE循环工作是一个多参数耦合和能量重新分配的复杂过程;执行器滞后引入的正时控制误差将是影响控制精度的重要因素。

To study piston movement characteristics of the hydraulic free piston engine（HFPE）,a simulation model of the HFPE was built up.The effects of cycle fuel delivery,injection timing,valve timing,compression pressure and load pressure on piston movement were investigated.Results indicate that these control variables can affect the forces applied on pistons,which varies the BDC position and engine compression ratio and performance.It is found that between expansion stroke and cycle fuel delivery,compression pressure and compression ratio exist approximate linear relation.The operation cycle of the HFPE is a complicated process coupled multiple variables and redistributed the energies applied on the pistons.The timing control error results from the actuator delay would be an important factor affecting control accuracy.