Free-piston linear generator

The first patents of free-piston linear generators date from around 1940, however in the last decades, especially after the development of rare-earth magnets and power electronics, many different research groups have been working in this field.

In the combustion chamber, a mixture of fuel and air is ignited, increasing the pressure and forcing the moving parts (connection rod, linear generator and pistons) in the direction of the gas spring.

The gas spring is compressed, and, while the piston is near the bottom dead center (BDC), fresh air and fuel are injected into the combustion chamber, expelling the exhaust gases.

The gas spring pushes the moving parts assembly back to the top dead center (TDC), compressing the mixture of air and fuel that was injected and the cycle repeats.

Several variations are possible for combustion: The Institute of Vehicle Concepts of the German Aerospace Center is currently developing a FPLG (or Freikolbenlineargenerator - FKLG) since 2002, and has published several papers about this subject.

[19] The German center is currently into its 2nd version of the entire system, on which two opposed cylinders will be used in order to reduce vibration and noise, making it viable for the automotive industry.