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Stirling engine

Ce site appartient au réseau de sites relatifs aux moteurs à air chaud

Other engines

There are other types of Stirling engines than those studied in the specific pages of this site. By taking the standard Gamma engine for reference, the principal models worthy of interest are the following:

Gamma engine Martini engine

Rigbom engine Free Stirling engine

1. The free piston engine or Martini engine :

The operating piston moves according to the pressure of the engine. When the pressure increases, it is pushed in one direction. When the pressure decreases, it returns in the other direction to its initial position. This requires the presence of an average force on the "outside" face of the piston, it is generated by a gas enclosed in a chamber or by the relief of a spring. If the piston engine is a magnet, one can install a linear alternator for generating electric current. (See above)

2. The free displacer engine or Ringbom engine: :

In contrast to the previous one, the piston is mechanically driven. The displacer moves according to the pressure of a gas enclosed in a capacity and the pressure of the engine (See above).

3. The free piston Stirling engine :

NASA engine

This engine combines the advantages of the previous models.The great advantage is that one can obtain an absolute sealing because there does not exist any mechanical connection with outside. Produced energy is evacuated by a completely tight linear alternator (See drawing above and the animation of NASA).

4. The double-acting piston engine :

The principle consists in putting several alpha engines in “series”. There is only one piston by cylinder which has the function of displacer and the function of operating piston. The phase angle difference between each piston is 90°.

Double-acting piston engine

5. The rotary engine :

In a first approch, this engine is like a Wankel rotary engine or a pallet compressor. It is a “square” which moves in an ellipse. The gas is confined between these two elements and sees the four phases of the Stirling cycle. Here is a very simplified representation and an animation.

Rotary engine Rotary engine Rotary engine Rotary engine

Rotary engine animation

6. The thermodynamic generator :

The thermodynamic generator


The ancestor of the free piston Stirling engine ?
The displacer oscillates with the pressure variations, it is supported by springs.
The operating piston is an elastic membrane actuating a magnet what makes it possible to generate an electric current by a linear alternator.

7. The fluidyne :

The fluidyne


Based on the cycle of Stirling, this device makes it possible to carry water. Except valves, there is no mechanical moving piece !

8. Yours ?

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This site was created and is maintained by Pierre Gras. Thank you with all the people who contributed their shares: articles, photographs, vidéos, worksheets… The author is opened with any suggestion allowing to improve this site for happiness of everybody. Finally, a big thank you to Robert Stirling !

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