Power Stars in the Future——Hydraulic Confined Piston Engine and Hydraulic Free Piston Engine

Development of hydraulic free piston engine(HFPE)and hydraulic confined piston engine(HCPE)was described, the comparative analysis of their structural principle and main performance character was carried out also. HFPE and HCPE can both directly transform thermal energy into hydraulic energy and be used as power source at full hydraulic vehicle. Using traditional combustion technology, the efficiency of HFPE reaches 40%, HCPE reaches 35%. In any working condition, they can easily work at optimal economic routine, recover braking energy and improve the efficiency of the entire vehicle.