Travail de fin d'études et stage[BR]- Travail de fin d'études : Modelling of the thermal behaviour of a high performance 2-speed-AMT transmission for Electric Vehicles and Characterisation of its water/oil cooler[BR]- Stage d'insertion professionnelle : VCST

Abstract

Electric vehicles are increasingly gaining prominence in the transport sector. Innovation in the automotive sector is moving quickly and therefore the development of some technologies as the high-performance 2-speed-AMT transmission for electric vehicles is an important issue. Thermal behaviour is a crucial aspect in the improvement of vehicle's gearbox efficiency and lifetime. Indeed, high temperatures damage components and oil, reducing the life of the transmission. The objective of this work is therefore to model the thermal behaviour of the transmission on Siemens LMS Imagine.Lab AMESim. For different operating points, power losses are calculated and so the efficiency is deduced. It results that the values obtained are close to the one measured on the test rig. Then, the temperatures of bearings, gears, housing and oil are computed. It is therefore possible to determine the temperature reached by components for each operating point. An oil cooler must be fitted on the gearbox to prevent the temperature from rising too high. The oil cooler used is a compact plate-fin heat exchanger with offset strip fins. It is experimentally and theoretically characterised. The results obtained in terms of dissipated heat and overall heat exchange coefficient show that despite the compactness of the heat exchanger, this one gives good performance. By taking into account its performance, it is then possible to determine which parameters, as the temperature difference and flow rates, are required to sufficiently cool the gearbox without exceeding the limits of the oil pump. In addition, the oil cooler model can be incorporated into the lubrication modelling in AMESim to provide a complete transmission model.