液压自由活塞发动机循环振动特性

Cyclic Vibration Characteristics of a Hydraulic Free-Piston Engine

研究单活塞液压自由活塞发动机循环振动特性。分析了自由活塞振动中的非线性因素,建立了非线性振动模型,根据其近似解对系统振动特性进行了分析和试验验证。结果表明,单活塞液压自由活塞发动机属于非对称恢复力自激振动系统。活塞循环振动过程是硬激励自激振动且存在稳定的极限环,其幅值随输入能量增加而增大,随工作压力的增大而减小。在定常振幅下,活塞振动过程呈现非对称性,且膨胀冲程最大速度较大。

Cyclic vibration characteristics of a single piston hydraulic free-piston engine are investigated.Nonlinear factors of the free-piston vibration are analyzed and a nonlinear vibration model for the free-piston is presented.An approximate solution of the model is given.Vibration characteristics are analyzed and validated by the experiment.Results indicate that the single piston hydraulic free-piston engine is a self-excited vibration system with unsymmetrical restoring forces.Piston cyclic vibration is a solid selfexcited vibration and has stable limit cycles.Amplitude increases with the increase of input power and the decrease of working pressure.Under the steady amplitudes,the piston motion is dissymmetric and maximum velocity is relatively large in the expansion stroke.