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The ongoing energy transition will have a profound impact on future mobility, with electrification playing a key role. Battery electric vehicles (EVs) are the dominant technology, relying on the conversion of alternating current (AC) from the grid to direct current (DC) to charge the traction battery. This process involves power electronic components such as rectifiers and DC/DC converters operating at high switching frequencies in the kHz range. Fast switching is essential to minimize losses and improve efficiency, but it might also generate electromagnetic interferences (EMI). Hence, electromagnetic compatibility (EMC) testing is essential to ensure reliable system operations and to meet international standards. During DC charging, the AC/DC conversion takes place off-board in the charging station, allowing for better cooling and larger components, resulting in increased power transfer, currently up to 350 kW.

There is a growing need for low-emissions concepts due to stricter emission regulations, more stringent homologation cycles, and the possibility of a ban on new engines by 2035. Of particular concern are the conditions during a cold start, when the Three-Way Catalyst is not yet heated to its light-off temperature. During this period, the catalyst remains inactive, thereby failing to convert pollutants. Reducing the time needed to reach this temperature is crucial to comply with the more stringent emissions standards. The post oxidation by means of secondary air injection, illustrated in this work, is a possible solution to reduce the time needed to reach the above-mentioned temperature. The strategy consists of injecting air into the exhaust manifold via secondary air injectors to oxidize unburned fuel that comes from a rich combustion within the cylinder.

Knocking is one of today’s main limitations in the ongoing efforts to increase efficiency and reduce emissions of spark-ignition engines. Especially for synthetic fuels or any alternative fuel type in general with a much steeper increase of the knock frequency at the KLSA, such as hydrogen, precise knock prediction is crucial to exploit their full potential. This paper therefore proposes a post-processing tool enabling further investigations to continuously gain better understanding of the knocking phenomenon. In this context, evaluation of local auto-ignitions preceding knock is crucial to improve knowledge about the stochastic occurrence of knock but also identify critical engine design to further optimize the geometry. In contrast to 0D simulations, 3D CFD simulations provide the possibility to investigate local parameters in the cylinder during the combustion.

For the NOx removal from diesel exhaust, the selective catalytic reduction (SCR) and lean NOx traps are established technologies. However, these procedures lack efficiency below 200 °C, which is of importance for city driving and cold start phases. Thus, the present paper deals with the development of a novel low-temperature deNOx strategy implying the catalytic NOx reduction by hydrogen. For the investigations, a highly active H2-deNOx catalyst, originally engineered for lean H2 combustion engines, was employed. This Pt-based catalyst reached peak NOx conversion of 95 % in synthetic diesel exhaust with N2 selectivities up to 80 %. Additionally, driving cycle tests on a diesel engine test bench were also performed to evaluate the H2-deNOx performance under practical conditions. For this purpose, a diesel oxidation catalyst, a diesel particulate filter and a H2 injection nozzle with mixing unit were placed upstream to the full size H2-deNOx catalyst.

The introduction of real driving emissions cycles and increasingly restrictive emissions regulations force the automotive industry to develop new and more efficient solutions for emission reductions. In particular, the cold start and catalyst heating conditions are crucial for modern cars because is when most of the emissions are produced. One interesting strategy to reduce the time required for catalyst heating is post-oxidation. It consists in operating the engine with a rich in-cylinder mixture and completing the oxidation of fuel inside the exhaust manifold. The result is an increase in temperature and enthalpy of the gases in the exhaust, therefore heating the three-way-catalyst. The following investigation focuses on the implementation of post-oxidation by means of scavenging in a four-cylinder, turbocharged, direct injection spark ignition engine. The investigation is based on detailed measurements that are carried out at the test-bench.

In this paper, the differences between a production car of the 2018 A-class and an early stage vehicle model with a mostly similar outer skin are examined experimentally and numerically. The aerodynamic development of vehicles at Mercedes-Benz is divided into several phases. When comparing force coefficients differences can be observed between these distinct hardware stages as well as when comparing steady state simulations to wind tunnel measurements. In early phases when prototype vehicles are not yet available, so-called aero foam models are used. These are well-defined full-sized vehicle models, as the outer skin is milled from Polyurethane. Important aerodynamic characteristics such as a motor compartment with a cooling module, deflecting axles with rotatable wheels and underbody covers are represented.

Intensified emission regulations as well as consumption demands lead to an increasing significance of unburned hydrocarbon (UHC) emissions for diesel engines. On the one hand, the quantity of hydrocarbon (HC) raw emissions is important for emission predictions as well as for the exhaust after treatment. On the other hand, HC emissions are also important for predicting combustion efficiency and thus fuel consumption, since a part of unreleased chemical energy of the fuel is still bound in the HC molecules. Due to these reasons, a simulation model for predicting HC raw emissions was developed for diesel engines based on a phenomenological two-zone model. The HC model takes three main sources of HC emissions of diesel engines into account: Firstly, it contains a sub-model that describes the fuel dribble out of the injector after the end of injection. Secondly, HC emissions from cold peripheral zones near cylinder walls are determined in another sub-model.

The industry is working intensively on the precision of thermal management. By using complex thermal management strategies, it is possible to make engine heat distribution more accurate and dynamic, thereby increasing efficiency. Significant efforts are made to improve the cooling efficiency of the engine water jacket by using 3D CFD. As well, 1D simulation plays a significant role in the design and analysis of the cooling system, especially for considering transient behaviour of the engine. In this work, a practice-oriented universal method for creating a 1D water jacket model is presented. The focus is on the discretization strategy of 3D geometry and the calculation of heat transfer using Nusselt correlations. The basis and reference are 3D CFD simulations of the water jacket. Guidelines for the water jacket discretization are proposed. The heat transfer calculation in the 1D-templates is based on Nusselt-correlations (Nu = Nu(Re, Pr)), which are derived from 3D CFD simulations.

For the gasoline engine, the isochoric process is the ideal limit of the ideal processes. During the project, a combustion engine with real isochoric boundary conditions is built. A “resting time” of the piston for several degrees crank angle in the top dead center (TDC) can be realized with a special crank drive. This crank drive consists of two crankshafts with different strokes, which are combined. The two crankshafts rotate with a ratio of two to one in opposite directions. The total stroke corresponds to the amount of the first crankshaft, so it is possible to investigate different strokes of the second crankshaft in the same crankcase. Different “resting times” can be achieved by different strokes of the second crankshaft. A specific combination of both crankshafts make a stroke possible which corresponds to that of a conventional combustion engine.

The reduction of engine-out emissions and increase of the total efficiency is a fundamental approach to reduce the fuel consumption and thus emissions of vehicles driven by combustion engines. Conventional passenger cars are operated mainly in lower part loads for most of their lifetime. Under these conditions, oil temperatures are far below the maximum temperature allowed and dominate inside the journal bearings. Therefore, the objective of this research was to investigate possible potentials of friction reduction by optimizing the combustion engine’s thermal management of the oil circuit. Within the engine investigations, it was shown that especially the friction of the main and connecting rod bearings could be reduced with an increase of the oil supply temperature. Furthermore, on a journal bearing test rig, it was shown that no excessive wear of the bearings is to be expected in case of load increase and simultaneous supply of cooler oil.

Engine valve flow coefficients are used to describe the flow throughput performance of engine valve/port designs, and to model gas exchange in 0D/1D engine simulation. Valve flow coefficients are normally determined at a stationary flow test bench, separately for intake and exhaust side, in the absence of the piston. However, engine operation differs from this setup; i. a. the piston might interact with valve flow around scavenging top dead center, and instead of steady boundary conditions, valve flow is nearly always subjected to pressure pulsations, due to pressure wave reflections within the gas exchange ports. In this work the influences of piston position and flow pulsation on valve flow coefficients are investigated for different SI engine geometries by means of 3D CFD and measurements at an enhanced flow test bench.

Engine valve flow coefficients are not only used to characterize the performance of valve/port designs, but also for modelling gas exchange in 0D/1D engine simulation. Flow coefficients are usually estimated with small pressure ratios and at ambient air conditions. In contrast, the ranges for pressure ratio, pressure and temperature level during engine operation are much more extensive. In this work the influences of these three parameters on SI engine poppet valve flow coefficients are investigated using 3D CFD and measurements for validation. While former investigations already showed some pressure ratio dependencies by measurement, here the use of 3D CFD allows a more comprehensive analysis and a deeper understanding of the relevant effects. At first, typical ranges for the three mentioned parameters during engine operation are presented.

The real cycle simulation is an important tool to predict the engine efficiency. To evaluate Extended Expansion SI-engines with a multi-link cranktrain, the challenge is to consider all concept specific effects as best as possible by using appropriate submodels. Due to the multi-link cranktrain, the choice of a suitable heat transfer model is of great importance since the cranktrain kinematics is changed. Therefore, the usage of the mean piston speed to calculate a heat-transfer-related velocity for heat transfer equations is not sufficient. The heat transfer equation according to Bargende combines for its calculation the actual piston speed with a simplified k-ε model. In this paper it is assessed, whether the Bargende model is valid for Extended Expansion engines. Therefore a single-cylinder engine is equipped with fast-response surface-thermocouples in the cylinder head. The surface heat flux is calculated by solving the unsteady heat conduction equation.

Longitudinal models are used to evaluate different vehicle-engine concepts with respect to driving behavior and emissions. The engine is generally map-based. An explicit calculation of both fluid dynamics inside the engine air path and cylinder combustion is not considered due to long computing times. Particularly for dynamic certification cycles (WLTC, US06 etc.), dynamic engine effects severely influence the quality of results. Hence, an evaluation of transient engine behavior with map-based engine models is restricted to a certain extent. The coupling of detailed 1D-engine models is an alternative, which rapidly increases the model computation time to approximately 300 times higher than that of real time. In many technical areas, the Fourier transformation (FT) method is applied, which makes it possible to represent superimposed oscillations by their sinusoidal harmonic oscillations of different orders.

As known de-icing methods use a high amount of energy or environmentally harmful chemicals, research has focused lately on passive de-icing by functional surfaces with an improved removal of ice (de-icing) or a reduced formation of it (anti-icing). Inspired by the Lotus plant leaf, a “superhydrophobic” surface can be produced by the combination of a hierarchical micro/nanoscale roughness and a hydrophobic surface coating. By a hot stamping process we have generated differently shaped microstructures (cylinders, ellipses) on polyurethane (PU) films which were afterwards coated by a plasma enhanced chemical vapor deposition (PECVD) process with thin, hydrophobic fluorocarbon films. This combination of methods could be a process for the production of large area functionalized films. PU films are suitable for outdoor use, because they are resistant against erosion and UV radiation. The films can be glued to different geometries and can easily be exchanged if damaged.

This report presents a new compensation method for distortions related to dead time, caused by B6-inverters with pulse-width-modulated output voltages. In spite of low sampling rates, the new method of compensation is effective at all ranges of rotation speed up to the field weakening region. No additional hardware is required for its implementation. The effectiveness of the new method has been shown experimentally. A description of the relevant distortions is given first to provide a basis for the development. This considers the field weakening region, and offers an illustrative method of quantifying the distortions. It is also shown that the use of compensation methods that do not take the sampling time into account leads to additional distortions. It is even possible that they exceed the distortions in an equivalent system without compensation.

Automotive electric and electronic devices are commonly tested with standard pulses at the battery lines according to ISO 7637-Part 1 and 2. As these pulses do not cover all disturbances that occur in modern passenger cars, each OEM defines its own additional test-pulses which makes it difficult for component suppliers to satisfy all existing requirements. The paper shows a comparison between measurement and simulation such as slow “ignition on” pulses of a modern passenger car. Additionally, the ability of the computing model to calculate the propagation of fast transients and characteristic pulses of currently used electric and electronic devices is demonstrated. This data can be used for the definition of new test-pulses.

In this paper the effects of pulsating blankholder forces in deep draw processes for sheet metal parts are discussed. Areas with and without tangential compressive stresses in the flanges, which are located between the binders, are discussed separately. Areas without tangential compressive stresses can be simulated by a special friction strip-draw test using a pulsating normal force ( representing the blankholder force ). Investigations using this equipment show that by pulsating blankholder forces it is possible to avoid galling and to reduce the friction force. Areas with tangential compressive stresses can be simulated by deep drawing axissymmetric cups using a pulsating blankholder force. Investigations with this equipment show that without increasing the danger of wrinkling the friction forces can be reduced by pulsating blankholder forces, when a certain frequency limit is reached.

The Institute for Polymer Testing and Polymer Science of the University of Stuttgart has been investigating automotive parts, structures and cars during their life cycle in plenty cooperation with the European automobile producers and their suppliers for the last 9 years. Therefore a holistic approach has been developed to combine tasks from technique, economic and environment in a methodology called Life Cycle Engineering (LCE). The goal is to find a way to support designer and engineers as well as police makers and public with this three-dimensional interrelated information to have the possibility to manufacture future products in a more sustainable way without loosing contact two the traditional parameters technique and costs.

The costs for development and production of draw dies for car outer panels are extremely high and should be reduced. Furthermore it is necessary to reduce the time for developing, designing and producing the dies for the production of parts. This paper discusses new press techniques, die designs and an adjustment program for press operators. The trend goes to single action presses with CNC-controlled multipoint cushion systems in the press table and to special designed dies. These systems lead to a more robust and reproducible forming process with improved product quality. This paper deals with: Cushion Systems, New Binder Designs for Draw Dies for Sheet Metal Automotive Parts, New Computer Program to Adjust the Blankholder Forces of Modern Hydraulic Cushion Systems of Single Action Presses and Pressure Measurement for Detecting the Pressure between the Blank and the Binders of Draw Dies for Sheet Metal Automotive Parts.