Thermodynamic device with a tension-compression coil spring system

A thermodynamic apparatus, comprising:

• a cylinder having a central axis;
• a displacer adapted to reciprocate within the cylinder;
• and
• a linear actuator which includes an armature coupled to the displacer and a spring system, wherein the spring system comprises:
• a first coil spring having a central axis;
• and
• a second coil spring having a rotational sense opposite to that of the first coil spring, wherein:
• central axes of the first and second coil springs are collinear with the central axis of the cylinder;
• a first end of the first coil spring is captured in a first plate coupled to the displacer;
• a second end of the first coil spring is captured in a second plate;
• a first end of the second coil spring is captured in the first plate;
• a second end of the second coil spring is captured in the second plate;
• a bending direction of the first coil spring, when a force is exerted along the central axis on the first coil spring, is estimated;
• a bending direction of the second coil spring, when the force is exerted on the second coil spring, is estimated;
• and
• points of capture of the ends of the first and second coil springs are selected so that the bending direction of the first coil spring is diametrically opposed to the bending direction of the second coil spring with respect to the central axis.