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« BMW to showcase AirTouch in Vision Car concept at CES | Main | New family of hydrophobic ionic liquid rocket propellants could replace hydrazine-based fuels » A consortium led by the Bosch Group has developed a standardized integrated diagnostic system that in the future will be able to clearly identify and locate defects in the electrical powertrain. The consortium’s project on diagnosis and repairs for electric vehicles—“DINA”—was funded with €2.8 million (US$3.1 million) by Germany’s Federal Ministry of Education and Research as part of the leading-edge “Electric Mobility South-West” cluster. Besides the Bosch Group, the consortium included DEKRA Automobil GmbH, the Fraunhofer Ernst-Mach-Institut, and the Research Institute of Automotive Engineering and Vehicle Engines Stuttgart (FKFS). The results of this research have important implications for suppliers, automakers, workshops, and testing organizations. Any company looking to succeed in the electric vehicle market needs a competitive aftersales concept. From July 2012 to July 2015, part of the DINA project was devoted to drawing up standards for the diagnosis and repair of high-voltage systems in electric vehicles and to researching suitable measurement methods. Consortium members also created an integrated diagnostic system to help detect and localize problems in an electric vehicle’s powertrain, from the high-voltage battery and inverter to the motors and charging system. This allows workshops to carry out “modularized repairs”. If it is possible to precisely determine where problems lie, there is no need to replace whole systems. Instead, in the future it will be possible to pinpoint and replace defective parts individually. This makes repairs not only faster, but also much more affordable. Being able to locate problems with precision is especially important when dealing with high-voltage batteries that consist of numerous independent cells. To make future battery systems easier to repair, the study also makes specific suggestions for how to build them. The diagnostic and repair methods the consortium has developed can now be contributed to the automotive industry’s development projects. A look at aftersales reveals how critical the DINA project’s research is. For example, flawless powertrain testing and diagnostics are an indispensable part of technical tests such as general vehicle inspections. What’s more, an electric vehicle’s value depends heavily on its condition, age, and the state of health of the valuable high-voltage battery. The project produced key insights into how to determine this state of health. Similarly, electrical powertrains call for new measuring devices and equipment for workshops and test benches. This is also an area the study addresses with recommendations and approaches for development work. With some 100 players from science and industry, the leading-edge “Electric Mobility South-West” cluster is an important regional associations in the field of electromobility. Coordinated by the regional agency e-mobil BW GmbH, the cluster aims to drive forward the industrial-scale manufacture of e-mobility in Germany and to establish the German state of Baden-Württemberg as one of the major providers of electromobility solutions. It brings together leading corporations and SMEs, especially those in the region covering Karlsruhe, Mannheim, Stuttgart, and Ulm, and networks them with local research institutions in four fields of innovation: vehicles, energy, information and communication technology, and production. In addition, the cluster features specialized working groups to ensure full coverage of all topics. The “intelligent move” working group, for instance, focuses on digitalization and automated driving.

Schmid A.,University of Stuttgart | Grill M.,Research Institute of Automotive Engineering and Vehicle Engines Stuttgart | Berner H.-J.,Research Institute of Automotive Engineering and Vehicle Engines Stuttgart | Bargende M.,Research Institute of Automotive Engineering and Vehicle Engines Stuttgart
SAE Technical Papers | Year: 2011

Turbocharged SI-DI-engines in combination with a reduction of engine displacement ("Downsizing") offer the possibility to remarkably reduce the overall fuel consumption. In charged mode it is possible to scavenge fresh unburnt air into the exhaust system if a positive slope during the overlap phase of the gas exchange occurs. The matching of the turbo system in SI-engines always causes a trade-off between low-end torque and high power output. The higher mass flow at low engine speeds of an engine using scavenging allows a partial solution of this trade-off. Thus, higher downsizing grades and fuel consumption reduction potential can be obtained. Through scavenging the global fuel to air ratio deviates from the local in-cylinder fuel to air ratio. It is possible to use a rich in-cylinder fuel to air ratio, whereas the global fuel to air ratio remains stochiometrical. This could be very beneficial to reduce the effect of catalytic aging on the one hand and engine knock on the other hand. Since the global fuel to air ratio is stoichiometric a post-oxidation of the unburnt fuel of the rich combustion process in the exhaust port is possible, if the unburnt fuel gets in contact with the unburnt scavenged fresh charge. Because of the intermittent mass flow of internal combustion engines the mixing of burnt and unburnt gas is quite difficult. Therefore, the effect of post-oxidation is highly dependent on the engine geometry and the operating conditions as well. The post-oxidation leads to a temperature increase in the exhaust system. Thereby the enthalpy of the exhaust gas increases as well. This higher exhaust enthalpy could enable higher boost pressures at lower engine speeds and a better transient engine response. In this paper an approach to model the effects of post-oxidation is presented. The simulations are done using 1-D flow calculation in combination with a phenomenological combustion and knock model. In the presented simulations a clear separation of the effect of scavenging with and without post-oxidation can be made. In real driving conditions, scavenging is mainly used during acceleration phases, so additional simulations were made under transient accelerations, too. Here, the presented transient calculations are considering crank angle based gas dynamics at every cycle and are embedded in a virtual vehicle simulation model. With these simulations the effects of post-oxidation in steady-state conditions as well as under transient acceleration conditions can be estimated and the benefit of a possible post-oxidation can be conceived. Copyright © 2011 SAE International.

Rether D.,University of Stuttgart | Grill M.,Research Institute of Automotive Engineering and Vehicle Engines Stuttgart | Schmid A.,University of Stuttgart | Bargende M.,Research Institute of Automotive Engineering and Vehicle Engines Stuttgart
SAE International Journal of Engines | Year: 2010

A new phenomenological CI combustion model was developed. Within this model the given injection rate may contain an arbitrary number of injections during one cycle. Another target was a short computation time of one second per cycle on average. The new approach should also have the ability to simulate a wide engine spectrum from passengercar engines through to marine engines. The ignition delay is calculated separately for each single injection. In this way the model depicts the influence of pilot injections on the ignition delay of proximate injections. Each pilot injection is modeled as a single air-fuel mixture cloud with air entrainment. The burn rate of the pilot injection is modeled as a function of flame propagation and of the current local excess air ratio. If the local excess air ratio becomes too lean the pilot combustion stops or does not start at all. Main and post-injections are calculated by means of a slice approach. The slices are generated isochronously as a function of the injection rate. They propagate through the combustion chamber in the direction of injection. Along the way the entrainment of air into the slices is computed by means of a statistical lambda distribution. The premixed and diffusion combustions are calculated by different approaches. Within the diffusion approach there is a distinction between the fast, nearly stoichiometric combustion and the slow lean combustion, which is responsible for the characteristic burn-out of CI combustion. The approach will be shown in detail. On the basis of measurements and simulations, the forecast capability and the limitations of the model are discussed in full. © 2010 SAE International.

Grill M.,Research Institute of Automotive Engineering and Vehicle Engines Stuttgart | Grill M.,University of Stuttgart | Bargende M.,Research Institute of Automotive Engineering and Vehicle Engines Stuttgart | Bargende M.,University of Stuttgart
SAE International Journal of Engines | Year: 2010

The main objective of the FVV-project "Cylinder Module" was the development of a profoundly modular designed concept for object-oriented modeling of in-cylinder processes of internal combustion engines. It was designed in such a way, that it can either be used as a stand-alone real working-process calculation tool or in tools for whole vehicle simulations. It is possible to run the "Cylinder Module"-code inside the FVV-"GPA"-software for transient vehicle and driving cycle simulations and it is possible to use the graphical user interface "ATMOS" of the "GPA"-project. The code can also be used as a user-subroutine in 1-D-flow simulation codes. Much effort was spent on the requirements of flexibility and expandability in order to be well prepared to cope with the diversity of both today's and future tasks. The code is freely available for members of the German Research Association for Combustion Engines (FVV). In the working-process calculation an analytical solution for the calculation of the difference quotients was developed, which is suitable for a user-defined number of zones in every thermodynamical system, too. As a consequence, exactly the same source code can be used for one-, two- or multi-zone calculations. In fact, additional zones can be switched on simply in case of need. It is possible to simulate a user-defined number of connected thermodynamical systems contemporaneously. © 2010 SAE International.

Wenig M.,University | Grill M.,Research Institute of Automotive Engineering and Vehicle Engines Stuttgart | Bargende M.,Research Institute of Automotive Engineering and Vehicle Engines Stuttgart
SAE International Journal of Engines | Year: 2013

For a reliable and accurate simulation of SI engines reproduction of their operation limits (misfiring and knock limit) and in this context the knowledge of cyclic combustion variations and their influence on knock simulation are mandatory. For this purpose in this paper a real working-process simulation approach for the ability to predict cycle-to-cycle variations (ccv) of gasoline engines is proposed. An extensive measurement data base of four different test engines applying various operation strategies was provided in order to gain a better understanding of the physical background of the cyclic variations. So the ccv initiated by dilution strategies (internal EGR, lean operation), the ccv at full load and at the knock limit could be investigated in detail. Finally, the model was validated on the basis of three further engines which were not part of the actual development process. In order to obtain a thorough understanding of the ccv phenomenology additionally the so-called residual gas feedback effect had to be examined. Therefore a one dimensional CFD simulation was implemented since in this case gas dynamic processes are essential. Basing on the final ccv model it was possible to evaluate the influence of a fluctuating combustion on knock simulation. A zero-dimensional knock model approach was implemented within the ccv model in order to ascertain the benefit maintained by single cycle resolved knock simulations. However, in correspondence with the measurement data analysis of knocking single cycles, it comes to a conclusion that an accurate prediction of knock phenomena requires the consideration of further influences beyond the mere influence of cyclic variations. Copyright © 2013 SAE International.

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