Robert Stirling stirling engine patent 1816

Stirling engine-
Hot air engine- Heissluftmotor-Moteur Stirling


The Stirlingengine was developed at the beginning of the 19th century among other things by Robbert Stirling (1790- 1878).
This hot air-engine, without valves and steam boiler had the potential to replace the more dangerous steam engine.

Due to the rapped development of the internal combustion engine and the electromotor the hot air-engine fell out of use.

When fossil fuels got scares in the second half of the last century the development of the hot air-engine was picked up again.

Philips designed from 1938-1969 several hot air-engines and these engines where used in submarines (Sweden) .
en in de space technology(NASA).

When the Stirling engine is driven by an electromotor, the engine is also suitable for cooling purposes.

In the future heating boilers using Stirling technology will not only provide heat, but also electricity and replace the present high efficiency heating boiler generation.



  • silent engine
  • few internal moving parts (reducing maintenance costs)
  • almost all fuels are suitable (such as garbage, bio-gas and solar energy)
  • high efficiency - 40 %
  • less CO2 emission

How it works

When the hot air-engine is heated from the outside, the energy is transmitted to the gas (air, helium) in a closed circuit (green). Thermal energy is converted into kinetic energy, heat becomes movement. The principle of the hot air-engine is based on the expansion and contraction of a gas by repeatedly heating and cooling of the gas.

  • heated air expands: volume and pressure increases
  • cooled air contracts; volume and pressure decreases

  • The red "piston" displaces the air forwards and backwards in the bottom cylinder. The heated air is displaced to the left to cool down. The cooled air is displaced to the right to warm up again. The left part of the displacer cylinder has a larger surface to increase the cooling process. The exchanging process goes very fast. Due to the developed volume- and pressure differences the top piston moves forwards and backwards. The piston fits exactly to prevent loose of pressure and drives the crankshaft with a connecting rod. On the crankshaft a flywheel is mounted, in which kinetic energy is stored and used to drive an application. This crankshaft also moves the displacer piston back- and forwards with a connecting rod. The angle shift between displacer- and power piston is always 90 °. By transposing the angle shift of one of the connecting rods by 180° the engine turns in opposite direction.
    The engine can not start on its one power.


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  • Stirlingsite with many videos, French

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    index the structure of an hotair-engine