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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.

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.

The Autark Hybrid is a parallel hybrid car concept with the aims of saving fuel, reducing exhaust gas, offering a zero emission driving mode and being autarkic from public power supply system. The drive line consists of a combustion engine, an electric engine and an i2-gearbox, a variable transmission with wide spreading. A controller system operates drive line according to an operation strategy and the drivers wish. For testing and investigation drive line is installed on a test rig. - After an introduction in the basics of the concept, test rig setup is described and measurement plots are shown.

Nowadays the task to diminish energy consumption and air pollution caused by road traffic occupies a key issue. One of several approaches is the hybrid driveline technology. At the Technical University Munich through a research project the “Optimized CVT-Hybrid-Powertrain” was designed and manufactured and is under investigation. This research project is run in close cooperation between university and industry (EPCOS AG, GM Powertrain Europe, ZF Friedrichshafen AG and ZF SACHS AG). The project is focused on reduction of fuel consumption at low additional cost for hybridization. The “Optimised CVT-Hybrid-Powertrain” is a full hybrid car driveline using Diesel-engine, electric motor with double layer capacitors for electric energy storage and a CVT-type transmission. Vehicle pull away is typically done by electric driving; the ic-engine is started by a fast ratio change of the CVT-transmission without additional starter.

During a special scientific project (SFB 365), supported by the DFG, a parallel hybrid concept for passenger cars, called the Autark Hybrid, was developed, assembled and investigated. The drive line consists an electric engine supplied by a 120V-Ni/MH-battery for about 30 km electrical driving distance and a turbo diesel engine. Both engines use the same gearbox, the i2-gearbox, which is specially designed to have a wide spreading. Significant fuel savings are achieved by recuperation of kinetic energy and by avoidance of inefficient operation of the ic-engine at areas of low power demand. The results from the research project concerning fuel consumption, respectively fuel saving will be presented and discussed in this paper. The adjustment between simulation and test rig investigations shows problems by the practical realisation of operation strategy and operation mode of the powertrain elements. As result smaller fuel savings can be realised than predicted.

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.