开发了一款用于小型车用有机朗肯循环( OＲC) 余热回收系统的新型自由活塞膨 胀机 －直线发电机( FPE-LG) ，并设计了一种新型配气机构来控制工质的进排气过程; 基 于压缩空气试验平台，对 FPE-LG 的运动特性、输出性能和指示效率进行了试验研究． 结 果表明:配气正时对 FPE-LG 的运动特性和输出性能具有重要影响; 活塞组件的行程和速 度随着进气角的增加而增大，随着排气角的减小而减小;优化配气正时可以明显改善直线 发电机的输出性能，在进气角为60°、排气角为180°的条件下，当进气压力为1． 9 ×105 Pa、 工作频率为2Hz、外接负载电阻为9Ω 时，FPE-LG 的峰值电压的最大值为 13 V、峰值功率 的最大值为18． 6W;随着外接负载电阻的增加，活塞组件的行程和速度呈现增加的趋势， FPE-LG 的峰值电压和峰值功率增大; FPE-LG 的指示效率随着外接负载电阻的增加而减 小，当进气压力为1． 9 ×105 Pa、工作频率为 3 Hz、外接负载电阻为3 Ω 时，FPE-LG 的指示 效率为66． 2%． 

 A new free piston expander-linear generator ( FPE-LG) prototype for small-scale organic Ｒankine cycle ( OＲC) waste heat recovery system was developed，and a new valve train was designed to control the intake and exhaust process of working fluid． The motion characteristics，output performance and indicated efficiency of the FPE-LG were investigated based on a compressed air test rig． The results show that the intake duration and exhaust duration have a great influence on the motion characteristics and output performance of the FPE-LG． The stroke and velocity of free piston assembly increase with the increase of the intake duration，and decrease with the decrease of the exhaust duration． the valve timing optimization can significantly improve the output power of linear generator． The maximum value of voltage is 13 V and the maximum value of peak power is 18. 6 W when the intake angle is 60°and the exhaust angle is 180°，and the intake pressure，operating frequency and the external load resistance are 1. 9 ×105 Pa、2 Hz and 9 Ω，respectively． The velocity and stroke of the free piston assembly show an increasing tendency，and higher peak voltage and power output，when the external load resistance increases． The indicated efficiency shows a downward tendency when the external load resistance increases． The indicated efficiency is 66. 2% when the external load resistance，operating frequency and the intake pressure are 3 Ω、3 Hz and 1. 9 ×105 Pa，respectively．