Fluid expansion engine

A hot fluid expansion engine comprising a central shaft and a plurality of actuator modules arranged in a star configuration around the central shaft, each module comprising:

• a drive piston movable in a first enclosure, the drive piston defining a working chamber of variable volume in said first enclosure;
• and
• a displacement piston movable in a second enclosure, the displacement piston separating a low temperature chamber of variable volume from a high temperature chamber of variable volume in said second enclosure, the low temperature chamber communicating with the working chamber;
• the drive piston and the displacement piston of each actuator module being connected to the central shaft via respective first and second eccentric transmissions, each of the first eccentric transmission and the second eccentric transmission being configured to cause the corresponding piston to perform reciprocating motion in translation, the motion of the drive piston having a phase lag of 90° relative to the motion of the displacement piston, each module being driven in rotation about the central shaft so as to accelerate the cooling of a fluid in the working chamber;
• the engine further including a fluid heater placed between the actuator modules, each high temperature chamber communicating with the fluid heater and each working chamber being connected to said fluid heater via a fluid circulation circuit, and the fluid circulation circuit of each actuator module includes a gas regenerator extending around the high temperature chamber.