| As a new type of vehicle power device,the free-piston engine has been researched throughout the domestic and foreign scholars due to its compact structure,high power density,strong fuel adaptability and high energy utilization.In this paper,a variable-stroke free-piston engine system was proposed based on the high design and control free-degrees of free-piston engine in order to ensure the engine system reaches the required performance under different conditions.The major contributions of this paper were as follows:(1)analyzed the requirements of free-piston engine system,and proposed the general plan for the engine system.Designed the implementation strategy in different running model and the stroke switch strategy of engine system with electromagnetic valvetrains.(2)analyzed the requirements of ECU for the free-piston engine,and proposed the control strategies for ignition system?fuel injection system?linear motor and valve system.Completed the hardware design and software development of ECU and finished the trial production.(3)completed the design of transformation and finished the construction of free-piston engine system.Tested the engine in four-stroke model and made the continuous and stable running of system which achieved good engine performance.(4)established and simulated the thermodynamic simulation model for free-piston engine in AVL Boost software.The simulation results of the simulation model were compared with the test results of the prototype system to verified the accuracy of the simulation model.(5)simulated the engine model in different injection parameters?ignition parameters and valve timing parameters to analysis the engine performance changing rules under two-stroke model.Built the joint simulation platform of AVL Boost and Matlab/Simulink based on the Particle Swarm Optimization to optimize the residual exhaust gas coefficient of engine system in two-stroke model,proposed an optimal gas distribution scheme for engine system. |
PDF Full Text Request