Study on the characteristics of a pneumatic spring with bellow

The performance of a single-chamber pneumatic spring and a dual-chamber pneumatic spring have much difference. Dynamical models of these two types pneumatic springs were built and the characteristics of them were analyzed in this paper. Based on the theory of engineering thermodynamic, gas state equations were established and the dynamical models were obtained. The results show that: the single-chamber pneumatic spring can be equivalent to three stiffness springs in parallel and the dual-chamber pneumatic spring can be equivalent to a stiffness spring and a damping in series, then connect with three stiffness springs in parallel. The stiffness and natural frequency are main influenced by chamber pressure, effective area, volume of the chamber, displacement. The stiffness increases with the chamber pressure increasing and decreases with the volume of the chamber increasing. Such an accurate model for the pneumatic springs would contribute to more effective design or control of vibration isolation systems.