Cylinder Volume Deviation for Heavy Duty Combustion Engines

Abstract: The automotive industry is a field of enormous competition. Customers and regulations demand economical and sustainable products. To achieve maximum efficiency, engine systems require detailed control. To increase the accuracy of the models that describe the combustion process, a demand has arisen at Scania for an exact prediction of the combustion chamber volume. During engine operation, the components surrounding the combustion chamber are exposed thermal forces, pressure forces and mass forces from the reciprocating components. Due to these forces, the components will deform and the volume of the combustion chamber will deviate from its ideal volume. During this master thesis, simulations have been carried out to calculate the mechanical deformations and approximate the combustion chamber volume deviation. The impact from production variations on the combustion chamber volume have been investigated. Based on the results from the simulations, a model has been implemented that approximates the combustion chamber volume based on linearized relations. The finished model gives reasonable results that are well in accordance with the time consuming simulations. The production variations have a relatively large impact on the combustion chamber volume and define the tolerances of the model.