Experimental Research Of Opposed-Piston Hydraulic Free Piston Engine

Compared with traditional internal combustion engine, an opposedpiston hydraulic free piston engine (OPHFPE) transmit, store and output energy indifferent way. It translates chemical energy of fuel combustion into hydraulic energythat then will be stored in a high pressure accumulator, and the hydraulic energyoutput work through the hydraulic motor. The compression ratio is flexible andcontrollable, the combustion state does not change with the load, and there is no sideforce on the piston.A finite element model of the solenoid valve, provides the basis for analysis, isestablished by Ansoft Maxwell. Meanwhile the experimental facility has also been setup. It indicates that the primary influence factors include shielding magnetism cushion,magnetic material and spring pre-tightening force, the secondary influence factor isthe free lift owing to it’s influence center on open response, and the tertiary one is themass of the moving parts.Because the two sides of the free piston engine not only follow the sameprinciple, but mirroring configuration, so experiment of the single sideengine has guiding significance for experiment of the whole engine. In this paper, asimple modification has applied to the engine, transforming the engine into asingle-piston hydraulic free piston engine, and take combustion experiment on it withdifferent compression ratio,different excess air coefficient and different working oilpressure.For OPHFPE, the synchronism of the two side pistons is vital, and theperformance of the solenoid valve mainly cause synchronization problem.To solve theproblem,we use the method of pulse compensation of the solenoid valve. It willexplained from two aspects, phase adjustment and pulse adjustment. Finally, thesynchronization effect is ideal.Finally, the combustion test of OPHFPE machine has been done. The fuel weused is ether, the compression ratio is23, excess air factor is1.84. In this cese,theengine realized compression ignition.