Research on piston movement dynamical simulation of hydraulic free piston engine

To study piston movement characteristics of the hydraulic free piston engine (HFPE), a simulation model of the HFPE was built up. The effects of cycle fuel delivery, injection timing, valve timing, compression pressure and load pressure on piston movement were investigated. Results indicate that these control variables can affect the forces applied on pistons, which varies the BDC position and engine compression ratio and performance. It is found that between expansion stroke and cycle fuel delivery, compression pressure and compression ratio exist approximate linear relation. The operation cycle of the HFPE is a complicated process coupled multiple variables and redistributed the energies applied on the pistons. The timing control error results from the actuator delay would be an important factor affecting control accuracy.