对置活塞二冲程内燃机折叠曲柄系方案设计研究

结合一种新型对置活塞内燃机折叠曲柄系设计要求，提出4种折叠曲柄系统方案，利用Matlab/Simulink和ADAMS建立了仿真模型，通过运动学和动力学特性分析进行方案优选。计算结果表明，与传统内燃机相比，这4种折叠曲柄系活塞运动学关于上止点具有明显的非对称性，相同转速下使得膨胀时间和压缩时间均不相同，因而将对气流湍动能、扫气质量和燃烧等容度均产生不同影响；动力学上，活塞侧压力较传统二冲程内燃机大幅度减小，有利于减小气缸壁的磨损。由于方案4具有空间结构布置灵活性大，系统平衡性较好，活塞运动规律有利于提高内燃机的充气效率和加快内燃机燃油与空气的混合速率，同时可以缩短着火延迟时期的特点，所以方案4为最优方案。

Design of Folded-cranktrain of Opposed-piston Two-stroke Internal Combustion Engine

Four design solutions are proposed for the folded-cranktrain of an advanced opposed-piston internal combustion engine. The kinematics and dynamics models of the proposed folded-cranktrains are established using Matlab/Simulink and ADAMS, and the best solution is obtained by analyzing the numerical simulation results. The results show that the piston kinematics characteristics of these four solutions are asymmetrical with respect to TDC, and the intake duration and compression duration are different compared with traditional internal combustion engine, which influences the turbulence intensity, scavenging quality and combustion isovolumetric degree. In view of dynamics, the lateral pressure of piston is much lower than that of traditional two-stroke internal combustion engine, which helps to reduce the abrasion of cylinder wall. Since Solution 4 has better spatial structure layout flexibility and system balance, the piston motion is conducive to the improvement in the charging efficiency of engine and the mixing rate of fuel and air; moreover, it also can shorten the ignition delay period, so Solution 4 is the optimal solution.