新型独立压缩自由活塞发动机仿真研究

摘要

In order to improve the performance of a four-stroke free-piston engine, a working cycle combined intake air independent compressed process with thermodynamic parameter controlled process is proposed here. A MATLAB/Simulink model is built up to analyse dynamic performances of the engine. The effects of intake pressures, ignition positions and lengths of expansion stroke on the engine are qualitatively analyzed. The simulation results show that the intake and compression processes change from serial to parallel, which shortens the intake and compression stroke, improves the efficiency and power of the system. Increasing the ignition position and compression ratio has a limited role on improving effective efficiency of the system. The operating load of the exhaust valve reduces by extending the expansion stroke. This model provides theoretical guidance for the improvement and test of the prototype.%为了提高四冲程自由活塞发动机系统的性能,该文提出了一种独立压缩、进气热力学参数可控的工作循环方案.利用MATLAB/Simulink建立系统动态仿真模型,获得了系统的基本特性,并进一步分析了进气压力、点火位置、膨胀行程长度等参数对系统性能的影响.仿真结果表明:新循环通过进气增压将缸内顺序进行的进气、压缩过程改为气缸内、外同时并行进行,缩短了缸内进气与压缩行程,显著提升了系统有效效率与输出功率；点火位置的提前和压缩比的增大对有效效率的提升作用有限；加大膨胀行程长度可降低排气门的工作负荷.通过模型的仿真分析为样机的改进与试验提供了理论指导.