Experiments on influencing parameters of hydraulic free piston diesel engine

Experimental study on operating parameters, start-up characteristics and operating characteristics were investigated in a single-piston hydraulic free piston engine. Results show that compression ratio can be controlled by changing the compression pressure. Cycle fuel amount, injection timing, exhaust valve timing, compression ratio and position of bottom dead center have the decisive role. Pulse width of frequency control valve signal affects engine start-up process. Short pulse width slows the piston movement or even is hard to start-up. Piston motion is asymmetry where compression stroke is longer than expansion stroke. Combustion process is nearly constant-volume combustion. Part of hydraulic energy output is lost because of slow response of valve.