rotary engine

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rotary engine,

internal-combustion engine whose cycle is similar to that of a piston engine, but which produces rotary motion directly without any conversion from reciprocating motion. A major problem associated with engines of this type is preventing the leakage of combustion gases. The only type of rotary engine currently considered to be of practical value is the Wankel engine (see internal-combustion engineinternal-combustion engine,
one in which combustion of the fuel takes place in a confined space, producing expanding gases that are used directly to provide mechanical power.
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). Although the gas turbine produces rotary motion directly, it is not generally considered a rotary engine because it functions differently.

Rotary Engine


an internal-combustion engine in which the energy of the combustion gases is converted into mechanical energy by means of a rotor that undergoes rotary or rotary-reciprocating motion relative to the body of the engine. The concept of the rotary engine, also called the rotary-piston engine, was first proposed in the 16th century, and several thousand patents for rotary engines have been registered. The first attempt to construct a working model of a rotary engine was in 1799, but the first practical rotary engine—the Wankel engine—only appeared in 1957.

In operation, the combustion chamber is formed by the surfaces of a rotor and the chamber walls; the volume of the chamber varies in a periodic manner as the cycles of compression and expansion of the working fluid are continuously repeated. Thus, rotary engines can have the same two-stroke and four-stroke operations characteristic of internal-combustion piston engines.

Modern rotary engines are produced with one, two, or three working sections—that is, one, two or three rotors, respectively, are located on a common eccentric shaft.


Khanin, N. S., and S. B. Chistozvonov. Avtomobil’nye rotorno-porshnevye dvigateli. Moscow, 1964.
Mototsikl: Teoriia, konstruktsiia, raschet. Moscow, 1971.


rotary engine

[′rōd·ə·rē ′en·jən]
(mechanical engineering)
A positive displacement engine (such as a steam or internal combustion type) in which the thermodynamic cycle is carried out in a mechanism that is entirely rotary and without the more customary structural elements of a reciprocating piston, connecting rods, and crankshaft.

Rotary engine

Internal combustion engine that duplicates in some fashion the intermittent cycle of the piston engine, consisting of the intake-compression-power-exhaust cycle, wherein the form of the power output is directly rotational.

Four general categories of rotary engines can be considered: (1) cat-and-mouse (or scissor) engines, which are analogs of the reciprocating piston engine, except that the pistons travel in a circular path; (2) eccentric-rotor engines, wherein motion is imparted to a shaft by a principal rotating part, or rotor, that is eccentric to the shaft; (3) multiple-rotor engines, which are based on simple rotary motion of two or more rotors; and (4) revolving-block engines, which combine reciprocating piston and rotary motion. See Automobile, Combustion chamber, Diesel engine, Gas turbine, Internal combustion engine, Otto cycle

References in periodicals archive ?
Called the Premacy Hydrogen RE Hybrid--the Mazda5 is known as the Premacy in Japan--the system transforms all engine output into electricity (the rotary engine is directly connected to a generator) and then uses that electricity to drive the permanent magnet synchronous motor to drive the wheels.
Figure 5 shows the variation of the volume of a rotary engine with the following specific parameters:
Now Mazda has come up with a much cleaner rotary engine, producing less pollution but without sacrificing power.
Mazda first started to develop the rotary engine in the 1960s, each development improving in power and reliability.
Announcing New Licensing Agreement For Rotary Engine Technology
The RX Vision had a rotary engine at the front, the drive wheels at the back and a very long bonnet, and is a spiritual successor to the third-generation FD RX-7 from the 1990s.
Contract notice: Rotary engine for a engineered wood pilot.
The 2010 IAHE Sir William Grove Award recognizes Mazda's initiatives to advance hydrogen energy, which include the commercialization of the world's first hydrogen rotary engine vehicles, and participation in Norway's national HyNor hydrogen project.
Carpet mats display the limited edition logo and stainless-steel scuff plates incorporate a 40th Anniversary Rotary Engine legend together with each car's number from 001 to 400.
Many companies built production rotary engine cars, Citroen produced a rotary GS in the early seventies and Chevrolet experimented with the engine in the 1960s but early unreliability scared off many manufacturers.