Development And Experimental Research Of Free Piston Expander-linear Generator Integrated Device

As a power output device of waste heat recovery system used for vehicle internal combustion engine, the selection and design of expander has a significant impact on its performance, the purpose of this project is to develop a expander used for vehicle waste heat recovery system.Through investigating the research and development works of expander, the design of free piston expander-linear generator integrated device is determined. Based on the characteristics of the free piston device, a novel valve train is designed. The dynamics analysis of valve train is used for determining its stable operating range and driving torque range, furthermore, valve control system with two servo motors and servo drivers is developed. According to the structure and operation of the free piston expander, a linear generator, compressed air source and experimental data acquisition system are coupled with the free piston expander. Finally, the free piston expander-linear generator integrated device test bench is developed.Based on the free piston expander-linear generator integrated device test bench, the influencing factors of intake pressure, cam disk rotation frequency and load resistance are discussed systematically. The results show that, with the increase of intake pressure, the distance of piston stroke increases, the piston peak velocity, peak acceleration and load peak voltage increases also. With the increase of cam disk rotation frequency, the cylinder peak pressure gradually reduces, the distance of piston stroke reduces, the piston peak velocity and load peak voltage showed a decreasing trend after the first increase. With the increase of intake pressure, the optimal cam disk rotation frequency increase. With the increase of load resistance, the piston peak velocity, peak acceleration and load peak voltage showed the first increase and then decreased also.The test results verify the feasibility of free piston expander-linear generator integrated device, and provide a reference and guidance for future research.