Pistonless rotary engine
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A pistonless rotary engine is an internal combustion engine that does not use pistons in the way a reciprocating engine does, but instead uses one or more rotors, sometimes called rotary pistons. An example of a pistonless rotary engine is the Wankel engine.
The term rotary combustion engine has been suggested as an alternative name for these engines 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.
Pistonless rotary engines
The pistonless rotary engine avoids the reciprocating motion of the piston engines with its inherent vibration and rotational-speed-related mechanical stress. The smoother ride and longer living engine are one of the reasons pistonless rotary engines have become so popular. As of 1964, the Wankel engine has been the only production pistonless rotary engine with the NSU Spyder produced by Felix Wankel and NSU. While Felix Wankel and Beauchamp Tower’s are the only production stage many engines have made it to the development stage and examples are listed under the Development stage of the article.. Examples of rotary engines include:
The Felix Wankel Rotary engine has been in production since the early 1960s and has been in many different manufacturers' cars. The most common production of the Wankel engine is in the Mazda rotary line up since the 1960s. Another example of the Wankel rotary is the two-stroke version. The two-stroke Wankel Engine, while very similar to the four strokes, has an increase in low-end torque and power. Like other versions of the two-stroke engines, Wankel Two strokes are not popular in mass production and are only used in specific cases such as industrial equipment and range extenders. Another version of the pistonless rotary engine that was produced was Beauchamp Tower’s Spherical Engine. The engine uses steam and a combination of disk chambers to create pressure powering the engine. The engine has been used for driving carriage lighting dynamos on locomotives.
- Beauchamp Tower's nineteenth century spherical steam engine (theoretically adaptable to use internal combustion)
- The Wankel engine
- Development stage
Engines under the development stage have been produced, whether by a company or individual, but have not been put into mainstream use. The engines listed below, while not a complete list, is a diverse number of engines that have not achieved the production stage that Tower’s and Wankel’s engine have received.
- The Engineair engine
- The Liquidpiston engine
- The Hamilton Walker engine
- The Libralato rotary Atkinson cycle engine
- The Quasiturbine
- The Ramgen Integrated Supersonic Component Engine
- The RKM engine, German: RotationsKolbenMaschine
- The Sarich orbital engine
- The Trochilic engine
- The Wave disk engine
- Conceptual stage
Unlike the previous stages, the conceptual stage didn’t reach past the drawing board. The only mainstream recorded engine to reach the conceptual stage and not attempt to reach development was the Gerotor engine. This engine was a positive displacement pump that used a cog to create power. The engine concept, as shown above, did not have an intake or exhaust system and was scrapped early in its production. The Gerotor, while only one in mainstream ideology, was not the only failed attempt of creating a more efficient rotary engine.
- The Gerotor engine
- Jan P. Norbye: 'Rivals to the Wankel: A Roundup of Rotary Engines', Popular Science, Jan 1967, pp 80-85.