Development of a Simulation Model of an Automatic Gearbox

A simulation model for an automatic gearbox with primary retarder has been constructed and implemented, in this thesis. Together with other modelled vehicle components, this model could for example be used for fuel consumption estimation or optimizing vehicle parameters. The mechanical components and the control system inside the automatic gearbox were modelled separately and then assembled into the final gearbox model, using the object-oriented programming language Modelica. Modelica ensures that each individual component can be reused in other models. The gearbox model was validated through a number of test cycles designed to capture different vehicle behaviours. The test cycles were recreated in the simulation environment and the simulation results could be compared to a real vehicle performing the same tests. Validation showed that the model succeeded in its goal, that the implemented model is reproducing similar behaviour as the real gearbox. With gear shifts taking place in about the same situations and converter locking/unlocking occurring the same time in the simu-lations as in the real vehicle testing