Modeling and Analysis of Pneumatic Cushioning Systems Under Energy-Saving Measures

Abstract

Pneumatic cylinder drives are widely used in automation technology—mainly for two reasons: They are cheap to acquire and easy to handle. At the same time, it is well known that there is a significant potential of energy savings when changing the control pattern from a standard scheme toward a task-specific scheme. In order to maintain a reliable operation and low wear of pneumatic cylinders, it is essential not to exceed the manufacturer’s specifications on kinetic impact energy at stroke end. Lowering the kinetic impact energy is typically done either by external shock absorbers (increasing the acquisition cost and requiring installation space) or internal solutions, i.e., pneumatic cushioning systems. In this article, we give a comprehensively identified and validated model extension to common modeling approaches for pneumatic cylinder drives regarding pneumatic end cushioning systems. Based on this model, we analyze, optimize, and evaluate the potential and applicability of energy-saving control strategies for pneumatic cylinder drives in the context of internal pneumatic cushioning systems. The results illustrate the large savings potential and point out which strategy is best to use for a specific application. Note to Practitioners —This article addresses the topic of energy efficiency of pneumatic drives, which are widely used in automation technology due to their low cost and high reliability. It is well known that pneumatic drives are often oversized and cause waste of energy. By changing the valve hardware and control pattern, energy savings of more than half of the compressed air consumption can be achieved as demonstrated in many scientific works. One main barrier to using such energy-saving strategies in practice is the concern about losing robustness. In this article, we analyze the influence of energy-saving strategies on impact velocity and the functionality of internal cushioning systems. By this, the robustness issue is addressed from two sides: the kinetic energy that needs to be absorbed at stroke end, and the kinetic energy that can be absorbed by internal damping systems. From a practical point of view, this contribution motivates and helps one to decide on the choice of energy-saving measures for pneumatic drives.