Pistonless rotary engine

This article is about pistonless design. For other uses of this term, see rotary engine (disambiguation). For the early piston design, see rotary engine.

Libralato engine

A pistonless rotary engine is an internal combustion engine that does not use pistons in the way a reciprocating engine does. Designs vary widely but typically involve one or more rotors, sometimes called rotary pistons, as described in QT-Wankel: Two Concepts 100 Years Apart ^[1] . Although many different designs have been constructed, only the Wankel engine has achieved widespread adoption.

The term rotary combustion engine has been used as a name for these engines^{[ citation needed ]} to distinguish them from early (generally up to the early 1920s) aircraft engines and motorcycle engines also known as rotary engines . However, both continue to be called rotary engines and only the context determines which type is meant, whereas the "pistonless" prefix is less ambiguous.

Pistonless rotary engines

A pistonless rotary engine replaces the linear reciprocating motion of a piston with more complex compression/expansion motions with the objective of improving some aspect of the engine's operation, such as: higher efficiency thermodynamic cycles, lower mechanical stress, lower vibration, higher compression, or less mechanical complexity. As of 2006 ^[update] the Wankel engine is the only successful pistonless rotary engine, but many similar concepts have been proposed and are under various stages of development. Examples of rotary engines include:

Production stage

• Wankel engine
• LiquidPiston engine
• Beauchamp Tower's nineteenth century spherical steam engine (in actual use as a steam engine, but theoretically adaptable to use internal combustion)

Development stage

• Engineair engine
• Hamilton Walker engines
• Libralato rotary Atkinson cycle engine
• Nutating disc engine
• Quasiturbine
• RKM engine, German : RotationsKolbenMaschine
• Sarich orbital engine
• Swing-piston engine, Trochilic
• Wave disk engine

Conceptual stage

• Gerotor engine
• Internally Radiating Impulse Structure: IRIS engine

See also

• Range extender (vehicle)

References

1. Gilles Saint-Hilaire; Roxan Saint-Hilaire; Ylian Saint-Hilaire; Françoise Saint-Hilaire (February 2025). "Comparative Analysis of Quasiturbine and Wankel Rotary Engine: Two Concepts 100 Years Apart" (PDF). International Journal of Science and Research. 14 (2). doi:10.21275/SR25210033851.

Further reading

• Jan P. Norbye: 'Rivals to the Wankel: A Roundup of Rotary Engines', Popular Science, Jan 1967, pp 80–85.
• Article referencing the October 1964 issue of Mechanix Illustrated and the AMC/Rambler rotary