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Wet running multi-plate clutches and brakes are important components of modern automotive and industrial powertrains. In the open stage, drag losses occur due to fluid shearing. This can subsequently lead to a perceptible reduction in the overall drivetrain efficiency. Injection or dip lubrication is used, depending on the application and the requirements. For the former a deep fundamental understanding already exists, whereas up until now the latter has not been extensively investigated. This contribution gives a detailed insight into the experimental research of the drag losses of wet running multi-plate clutches at dip lubrication. In a base study, the flow conditions and origins of the drag torque generation were investigated. Built on this, the effects of operating and geometry parameters, such as oil viscosity and level, clearance, groove design, plate size and number of gaps on the drag loss characteristic, were determined based on full factorial testing.

Wet-running multi-plate clutches and brakes are important components of modern powershift gearboxes and industrial powertrains. In the open stage, drag losses occur due to fluid shear. The identification of drag losses is possible by experiment or CFD-simulation. For the calculation of the complex fluid flow of an open clutch, CFD-approaches such as the volume of fluid (vof) method or the Singhal cavitation model are applicable. Every method has its own specific characteristics. This contribution sets up CFD-calculation models for different clutches with diverse groove designs. We present results of calculations in various operating conditions obtained from the Singhal cavitation model and the vof method. The usage of modern commercial CFD-Tools (Simerics MP+) results in short calculation times.

Downsizing and downspeeding are currently important development approaches of the automobile industry to improve fuel efficiency and to reduce emissions. Decreased operational speeds in combination with higher combustion pressures lead to an increase of the excitation of torsional vibrations by the combustion engine. Torsional vibrations in powertrains can cause strength and NVH problems as well as lower driving comfort and reliability of the vehicle. Currently, conventional systems for reduction of torsional vibrations are increasingly reaching their limits. In cooperation with several institutes of the Technische Universität München (TUM) innovative concepts for an improved reduction of torsional vibrations in automotive powertrains have been developed.