The method of adding expansion work to pneumatic actuators is studied for
classical linear cylinders. The operating principle of new cylinder assemblies is
presented. A first simulation set illustrates the performance of the new assembly and
tries to define the parameters of a single cylinder which produces the same mechanical
performance. Acceleration, speed and reached position within a given time are the
conditions for the comparison. Then, the air consumption of both compared systems is
calculated. With an experimental set-up, a parasitic effect is observed, which consists
of a pre-expansion transient due to parasitic dead volumes related to the tubing and
internal volumes of the valves. A second assembly is realized with larger volumetry in
order to observe the dependency of the parasitic effect from the size of the cylinders.
For the control, a system with simpler control valves is also studied.
Keywords: Adiabatic expansion, Cylinder assemblies, Dead volumes, Energetic performance, Energy efficiency, Expansion work, Linear cylinders.
