对置活塞二冲程内燃机折叠曲轴系统动力学分析

Dynamics Analysis of Folded-Crank Mechanism of Opposed-Piston Two-Stroke Engine

运用理论力学和发动机动力学的基本理论,对所提出的折叠曲轴系统建立了运动学和动力学分析模型,并利用MATLAB/Simulink建立仿真模型进行动力学特性分析。结果表明:与传统发动机相比,该内燃机活塞运动学关于上止点具有明显的非对称性,相同转速下使膨胀时间延长而压缩时间缩短,提高了上止点附近气流湍动能,有利于增强上止点附近的气体紊流强度,燃烧等容度也有所增加;但换气时间变短,影响换气质量;动力学上,活塞侧压力较传统二冲程发动机大幅度减少,有利于减少气缸壁的磨损。

Established kinematics and dynamics model of proposed folded-crank mechanism based on theoretical mechanics and engine dynamics, calculations on kinematics and dynamics were conducted using MATLAB/Simulink emulator. Simulation results show that kinematic characteristics of engine piston is asymmetry about TDC, different with the traditional engine. In the same speed, owing to extended expansion duration and shortened compression duration, the turbulence intensity near TDC and combustion isovolumetric degree are increased; however, ventilation time becomes short, deteriorating gas exchange quality. In view of dynamics, the lateral pressure of piston is significantly lowered than traditional two-stroke engine, beneficial to reduction of cylinder liner wear.