Investigations for a Trajectory Variation to Improve the Energy Conversion for a Four-Stroke Free-Piston Engine

Applied Sciences

Roberto Leidhold¹  Andreas Gerlach¹  Sebastian Benecke¹  Robin Tempelhagen²  Kevin Klepatz²  Hermann Rottengruber² 

[1]Department of Electric Power Systems, Otto-von-Guericke University, 39016 Magdeburg, Germany

[2]Department of Mobile Systems, Otto-von-Guericke University, 39016 Magdeburg, Germany

关键词: free-piston engine;    linear permanent magnet synchronous machine;    four-stroke;    energy-conversion;    efficiency improvement;   

DOI  :  10.3390/app11135981

来源: DOAJ

【 摘 要 】

Internal combustion engines with a crankshaft have been successfully developed for many years. They are lacking in the fact that the piston trajectory, i.e., position as a function of time, is limited by the crankshaft motion law. Position-controlled electric linear machines directly coupled to the piston allow to realize free-piston engines. Unlike the crankshaft-based engines, they allow for a higher degree of freedom in shaping the piston trajectory, including adaptive compression ratios, which enables optimal operation with alternative fuels. The possibility of adapting the stroke course results in new degrees of freedom with which the combustion process can be optimized. In this work, four-stroke trajectories with different amplitudes and piston dynamics have been proposed and analyzed regarding efficiency. A simulation model was created based on experimental measurements for testing the proposed trajectories. It could be proved that the variation of the trajectory resulted in an improvement of the overall efficiency. The trajectories were described analytically so that they can be used for a prototype in a future work.

【 授权许可】

Unknown