Modeling of a Novel Fan Clutch Pneumatic Actuation System

A variable speed fan clutch system has been developed to help improve engine temperature regulation efficiency in heavy-duty commercial vehicles. This system is currently in a prototype phase and a detailed physical model of the actuation system is required for control system design and design trade-off analysis. This paper proposes the use of model identification techniques to estimate a minimal model structure. Parametric models of the fan clutch pneumatic system are developed and the system dynamic behavior examined. The fan clutch pneumatic system is composed of three subsystems. Model structure estimates for these sub-systems are realized using system identification techniques. The physical and parametric models are validated by comparing simulation and test results. A comparison of the physical and parametric models shows that the physical models outperform the identified parametric models and are able to closely predict the system response to a range of inputs.