![Rotary Engine Photo Sequence 01](https://upload.wikimedia.org/wikipedia/commons/f/fa/Rotary_Engine_Photo_Sequence_01.gif)
A pistonless rotary engine is an
internal combustion engine
An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal c ...
that does not use
pistons in the way a
reciprocating engine
A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert high temperature and high pressure into a rotating motion. This article describes the common fea ...
does. Designs vary widely but typically involve one or more
rotor
Rotor may refer to:
Science and technology
Engineering
* Rotor (electric), the non-stationary part of an alternator or electric motor, operating with a stationary element so called the stator
*Helicopter rotor, the rotary wing(s) of a rotorcraft ...
s, sometimes called rotary pistons. Although many different designs have been constructed, only the
Wankel engine
The Wankel engine (, ) is a type of internal combustion engine using an eccentric rotary design to convert pressure into rotating motion. It was invented by German engineer Felix Wankel, and designed by German engineer Hanns-Dieter Paschke. ...
has achieved widespread adoption.
The term rotary combustion engine has been used as a name for these engines to distinguish them from early (generally up to the early 1920s)
aircraft engines and
motorcycle engine
A motorcycle engine is an engine that powers a motorcycle. Motorcycle engines are typically two-stroke or four-stroke internal combustion engines, but other engine types, such as Wankels and electric motors, have been used.
Although some moped ...
s also known as ''
rotary engine
The rotary engine is an early type of internal combustion engine, usually designed with an odd number of cylinders per row in a radial configuration. The engine's crankshaft remained stationary in operation, while the entire crankcase and its ...
s''. 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
A thermodynamic cycle consists of a linked sequence of thermodynamic processes that involve transfer of heat and work into and out of the system, while varying pressure, temperature, and other state variables within the system, and that eventual ...
, lower
mechanical stress
In continuum mechanics, stress is a physical quantity. It is a quantity that describes the magnitude of forces that cause deformation. Stress is defined as ''force per unit area''. When an object is pulled apart by a force it will cause elonga ...
, lower vibration, higher
compression
Compression may refer to:
Physical science
*Compression (physics), size reduction due to forces
*Compression member, a structural element such as a column
*Compressibility, susceptibility to compression
* Gas compression
*Compression ratio, of a ...
, or less mechanical complexity. 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
The Wankel engine (, ) is a type of internal combustion engine using an eccentric rotary design to convert pressure into rotating motion. It was invented by German engineer Felix Wankel, and designed by German engineer Hanns-Dieter Paschke. ...
*
LiquidPiston engine
* Beauchamp Tower's nineteenth centur
spherical steam engine(in actual use as a steam engine, but theoretically adaptable to use internal combustion)
;Development stage
*
Engineair engine
*
Hamilton Walker engine
* Libralato rotary
Atkinson cycle
The Atkinson-cycle engine is a type of internal combustion engine invented by James Atkinson in 1882. The Atkinson cycle is designed to provide efficiency at the expense of power density.
A variation of this approach is used in some modern auto ...
engine
*
Quasiturbine
The Quasiturbine or Qurbine engine is a proposed pistonless rotary engine using a rhomboidal rotor whose sides are hinged at the vertices. The volume enclosed between the sides of the rotor and the rotor casing provide compression and expansion i ...
*
RKM engine
The Rotary Piston Machine (german: Rotationskolbenmaschine (RKM)) is a proposed (still in development) form of machine. It can be used either to transform pressure into rotational motion (an engine), or the converse - rotational motion into pressu ...
, german: RotationsKolbenMaschine
*
Sarich orbital engine
The Sarich orbital engine is a type of internal combustion engine, invented in 1972 by Ralph Sarich, an engineer from Perth, Australia, which features orbital rather than reciprocating motion of its central piston. It differs from the conceptual ...
*
Trochilic engine
A swing-piston engine is a type of internal combustion engine in which the pistons move in a circular motion inside a ring-shaped "cylinder", moving closer and further from each other to provide compression and expansion. Generally two sets of pis ...
*
Wave disk engine A wave disk engine or wave disk generator is a type of pistonless rotary engine being developed at Michigan State University and Warsaw Institute of Technology. The engine has a spinning disk with curved blades. Once fuel and air enter the engine, ...
*
Nutating disc engine
A nutating disc engine (also sometimes called a disc engine) is an internal combustion engine comprising fundamentally of one moving part and a direct drive onto the crankshaft. Initially patented in 1993, it differs from earlier internal combu ...
;Conceptual stage
*
Gerotor
A gerotor is a positive displacement pump. The name ''gerotor'' is derived from "generated rotor". A gerotor unit consists of an inner and outer rotor. The inner rotor has ''n'' teeth, while the outer rotor has ''n''+1 teeth; with ''n'' defined a ...
engine
*
Integrated Supersonic Component Engine
The IRIS Engine is a design for a new type of internal combustion engine. Its inventors say that engines constructed using this design can be smaller, lighter and significantly more efficient than traditional engines of comparable horsepower and ...
See also
*
Range extender (vehicle)
A range extender is a fuel-based auxiliary power unit (APU) that extends the range of a battery electric vehicle by driving an electric generator that charges the vehicle's battery. This arrangement is known as a series hybrid drivetrain. The m ...
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
{{Authority control
Pistonless rotary engine,
Proposed engines
Engine technology
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