LiquidPiston

The LiquidPiston engine is a pistonless rotary engine that operates on the high-efficiency hybrid cycle.[1] [2] This cycle consists of compressing air (with no fuel) to a very high ratio, as is typical in the Diesel cycle. The air is then isolated in a constant volume chamber. Fuel is injected and allowed to combust fully under constant volume conditions, which is how Otto cycle combustion is modeled. Finally, the combustion products are expanded to atmospheric pressure, utilizing the Atkinson cycle.

In the Wankel engine, the only successful pistonless rotary engine to date, an oval housing surrounds a triangular rotor. The three operating chambers thus formed are separated by seals installed on the three apexes of the rotor. These seals move in and out during each rotation, and are subjected to high stresses and wear; as a result they have been the limiting factor in longevity of such engines.

The LiquidPiston design reverses the shapes: an oval rotor moves within a triangular housing. The required seals (both face and apex) are mounted on the stationary housing, and are lubricated directly.

In order to use the Diesel cycle efficiently, high compression ratios are required. Typical piston diesel engines use 15 to 24 to 1. The projected compression ratio of the LiquidPiston engine is 26:1.[3]


References

  1. ↑ Shkolnik N., Shkolnik A. “High Efficiency Hybrid Cycle Engine”, Proceedings of the ASME Internal Combustion Engine Division 2006 Spring Technical Conference.
  2. ↑ Nabours, S., Shkolnik, A., Shkolnik, N., Nelms, R., Gnanam, P. “2010 SAE World Congress: High Efficiency Hybrid Cycle Engine”, Society of Automotive Engineers, World Congress, April 2010, Detroit, MI, USA. Paper 2010-01-1110. Archived 29 February 2012 at the Wayback Machine.
  3. ↑ Warwick, Graham. Liquid Piston's Rotary Engine Could Revolutionize UAS . . Aviation Week & Space Technology, 8 June 2018
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