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The new generation of automatic transmissions is characterized by a compact and highly efficient design. By the use of a higher overall gear ratio and lightweight components combined with optimal gear set concepts it is possible to improve significantly fuel consumption and driving dynamics. Precise and efficient real time models of the whole power train including models for complex subsystems like the automatic transmission are needed to combine real hardware with virtual models on XiL test rigs. Thereby it's possible to achieve a more efficient product development process optimized towards low development costs by less needed prototypes and shorter development times by pushing front loading in the process. In this paper a new real time model for automatic transmissions including approved models for the torque converter, the lock-up clutch and the torsional damper are introduced. At the current development stage the model can be used for comfort analysis and drivability assessment.

The authors want to introduce a general methodology for the simulation of the dynamics of the piston-liner contact considering a realistic oil film at inner liner wall. Because of the complexity of this problem and in order to minimize computing time a twin model was developed. Firstly, a simplified model is used to compute piston motion trends and piston ring lubrication in minimum simulation time. Secondly a very detailed model simulating multi-body dynamics, surface vibrations and elasto-hydrodynamic contact is applied. Both, the theoretical background of the twin model and the advantages of the coupled simulation procedure given in the wide range of considerable influences are discussed. The result examples focus on interaction effects of piston secondary movement and the influence of the available oil film. Finally, the status of verification of the models using measured results is shown.

Due to durability and lifetime requirements, the timing drive systems of modern passenger car engines are often equipped with chain drives. Chain driven systems are usually more critical in view of NVH compared to synchronous belt-drives. Mainly the polygonal effect and the related phenomena, like impacts caused by the meshing between the chain-links and impacts in the engagement/disengagement regions of guides and sprockets, lead to an increased excitation of the engine's structure. Since the polygonal effect occurs with the meshing frequency, the excited vibrations are basically narrow banded and can finally be recognized as an annoying whine-noise. This paper describes the modeling (MBS) of the entire timing-drive system containing a bushing-chain-drive, camshafts and all connected single valve trains. The investigations carried out are mainly focused on the primary dynamics of the chain drive and the forces which are transferred to the engine's structure.