Modeling the pneumatic relay valve of an s-cam air brake

Abstract

Statistics indicate that defects in brake system contribute significantly to fatal crashes involving commercial vehicles. Hence there is a need for developing preventive and active safety measures for assessing the performance of an air brake system in trucks. Existing techniques for assessing the performance of brakes are infrastructure intensive, time and labor intensive. The premise of this thesis is that model-based diagnostic techniques can be employed to overcome these limitations of existing tech- niques. The design of a model-based diagnostic system requires the development and experimental corroboration of a mathematical model of the evolution of pressure in each brake chamber of a truck in response to the application of brake pedal input by the driver, when there are no faults or defects in the brake system. This thesis is aimed at modeling and experimentally corroborating a subsystem of an air brake system, namely the pneumatic relay valve. The pneumatic relay valve takes a input signal from the primary delivery of a treadle valve and meters air from a storage reservoir to Type 30 rear brake chambers. A description of the development of the model, the experimental setup and corroborating experimental results are provided.