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Viewing 1 to 30 of 81
2005-05-16
Technical Paper
2005-01-2325
Christian Y. Glandier, Ralf Lehmann, Takashi Yamamoto, Yoshinobu Kamada
This paper investigates the potential of using FEA poro-elastic Biot elements for the modeling carpet-like trim systems in a simplified setup. A comparison between FEA computations and experiments is presented for two layer (mass-spring) trim systems placed on a test-rig consisting in a 510×354×1.6 mm flat steel plate clamped in a stiff frame excited at its base. Results are presented for a given heavy layer with two different poro-elastic materials: one foam and one fibrous material. The investigations included accelerometer measurements on the steel plate, laser-doppler vibrometer scans of the heavy layer surface, sound pressure measurements in free field at a distance of 1 meter above the plate, as well as sound pressure in a closed rectangular concrete-walled cavity (0.5×0.6×0.7 m) put on top of the test-rig. Computations were carried out using a commercial FEA software implementing the Biot theory for poro-elastic media.
2006-04-03
Technical Paper
2006-01-0232
G. Lepperhoff, Th. Körfer, Stefan Pischinger, H. Busch, S. Keppeler, P. Schaberg, M. Schnell
In view of limited crude oil resources, alternative fuels for internal combustion engines are currently being intensively researched. Synthetic fuels from natural gas offer a promising interim option before the development of CO2-neutral fuels. Up to a certain degree, these fuels can be tailored to the demands of modern engines, thus allowing a concurrent optimization of both the engine and the fuel. This paper summarizes investigations of a Gas-To-Liquid (GTL) diesel fuel in a modern, post-EURO 4 compliant diesel engine. The focus of the investigations was on power output, emissions performance and fuel economy, as well as acoustic performance, in comparison to a commercial EU diesel fuel. The engine investigations were accompanied by injection laboratory studies in order to assist in the performance analyses.
2005-04-11
Technical Paper
2005-01-1899
Marco Braun, Roland Caesar, Dirk Limperich, Katrin Prölß, Gerhard Schmitz
Development times in the automotive industry are becoming increasingly shorter. For this reason, design decisions based on simulation results must be made at an early development stage. The dynamic simulation of an automotive refrigeration cycle with Dymola/Modelica as part of the design process will be described in the following paper. The component supplier's expertise as well as the automotive manufacturer's knowledge of vehicle parameters in one simulation platform will also be discussed.
2005-05-11
Technical Paper
2005-01-2187
Paul Schaberg, Johan Botha, Mark Schnell, Hans-Otto Hermann, Norbert Pelz, Rudolf Maly
The results of a comprehensive experimental investigation into the exhaust emission performance and combustion properties of neat and blended Gas-To-Liquids (GTL) diesel fuel are presented. A sulphur-free European diesel fuel was used as the reference fuel, and two blends of the GTL diesel fuel with the reference fuel, containing 20% and 50% GTL diesel fuel respectively, were investigated. The study was based on a Mercedes Benz 2.2 liter passenger car diesel engine and presents emission data for both the standard engine calibration settings, as well as settings which were optimized to match the characteristics of each fuel. Vehicle emission tests showed that the GTL diesel fuel results in reductions in HC and CO emissions of greater than 90%, while PM is reduced by 30%, and NOx remains approximately unchanged. Engine bench dynamometer tests showed reductions in soot of between 30% and 60%, and NOx reductions of up to 10% with the GTL diesel fuel, depending on the operating point.
2005-04-11
Technical Paper
2005-01-1696
Wolfgang Hauer, Hans Peter Großmann, Günter Stöhr
Because of the rapidly increasing amount of electronic components and busses in a vehicle, the use of gateways in Electronic Control Units (ECUs) becomes more important. The upcoming question is how to design an optimal gateway. This paper describes a method for designing an optimal automotive gateway in an FPGA by using Evolutionary Algorithms (EAs). The complete gateway functionality is diagrammed in a specification graph which consists of a function graph and an architecture graph. The function graph describes the complete functionality of the gateway. The architecture graph shows the variety of the different implementation options of the mapped function graph. Each gateway task in the function graph can be realized either in a parallel way (different kinds of hardware implementations) or in a sequential way (software on a microprocessor core).
2006-04-03
Technical Paper
2006-01-1240
Mirko Conrad, Heiko Dörr, Ines Fey, Ingo Stürmer
In the automotive industry, the model-based approach is increasingly establishing itself as a standard paradigm for developing control unit software. Just as code reviews are widespread in classical software development as a quality assurance measure, models also have to undergo a stringent review procedure – particularly if they serve as a starting point for automatic implementation by code generators. In addition to these model reviews, the generated production code is reviewed later in the development process by performing auto code reviews. This article will present procedures for and give an account of experiences with model and code reviews which have been adapted to the model-based development process.
2005-06-14
Technical Paper
2005-01-2736
Junhong Dai, Yu Teng
Boundary mannequin is an important concept in digital human modeling and simulation, yet complicated to deal with and utilize. In theory, the number of boundary mannequins could be as much as (n!)2n for a single gender, where n is the number of critical anthropometric dimensions. It has been recommended [1] to break a complicated task into smaller tasks to reduce the scale of problem, and limit n=2 whenever possible. Even then, the number of boundary mannequins is still high for simulations. In this paper, the authors intend to further simplify the issue. An Excel worksheet is created for the purpose. The input can be as few as two points. An ellipse representing the boundary is automatically generated through regression analysis, and the extremes on the major and minor axes of the ellipse are then obtained, and taken as the optimal boundary mannequins.
2006-04-03
Technical Paper
2006-01-0411
Clemens Brinkmeier, Christof Schön, Guido Vent, Christian Enderle
Automotive catalysts close coupled to gasoline engines operated under high load are frequently subjected to bed temperatures well above 950 °C. Upon deceleration engine fuel cut is usually applied for the sake of fuel economy, robustness and driveability. Even though catalyst inlet gas temperatures drop down immediately after fuel cut - catalyst bed temperatures may rise significantly. Sources for catalyst temperature rise upon deceleration with fuel cut are discussed in this contribution.
2005-10-23
Technical Paper
2005-26-356
Sanjeev Mandpe, Suhas Kadlaskar, Winfried Degen, Stefan Keppeler
This paper addresses the use of neat, indigenous biodiesel in advanced Mercedes-Benz passenger cars. Modern, unmodified EU3 Common-Rail diesel engines with second generation common rail technology were used to determine the effects of neat biodiesel on performance and emission characteristics. The biodiesel was made from the seeds of the Jatropha Curcas plant and sourced from the Central Salt and Marine Chemicals Research Institute in Bhavnagar, India. The production of biodiesel and the vehicle tests are part of a PPP project, funded jointly by the DaimlerChrysler AG and the German DEG. The project aims at providing additional jobs and income in rural Indian areas along with reclaiming unused wasteland. The test vehicles were operated for a cumulative 8000 kilometers with an intention to expose the vehicle and fuel to diverse climatic conditions.
2007-01-23
Technical Paper
2007-01-0027
Paul Schaberg, Johan Botha, Mark Schnell, Hans-Otto Herrmann, Stefan Keppeler, Walter Friess
A Mercedes E320 CDI vehicle has been modified for more optimal operation on Gas-To-Liquids (GTL) diesel fuel, in order to demonstrate the extent of exhaust emission reductions which are enabled by the properties of this fuel. The engine hardware changes employed comprised the fitment of re-specified fuel injectors and the reduction of the compression ratio from 18:1 to 15:1, as well as a re-optimisation of the software calibration. The demonstration vehicle has achieved a NOx emission of less that 0.08 g/km in the NEDC test cycle, while all other regulated emissions still meet the Euro 4 limits, as well as those currently proposed for Euro 5. CO2 emissions and fuel consumption, were not degraded with the optimised engine. This was achieved whilst employing only cost-neutral engine modifications, and with the standard vehicle exhaust system (oxidation catalyst and diesel particulate filter) fitted.
2007-01-23
Technical Paper
2007-01-0035
Rudolf R. Maly, Volker Schaefer, Heinz Hass, G. F. (Barry) Cahill, Pierre Rouveirolles, Anders Röj, Rainer Wegener, Xavier Montagne, Alessandra Di Pancrazio, Julian Kashdan
Over the next decades to come, fossil fuel powered Internal Combustion Engines (ICE) will still constitute the major powertrains for land transport. Therefore, their impact on the global and local pollution and on the use of natural resources should be minimized. To this end, an extensive fundamental and practical study was performed to evaluate the potential benefits of simultaneously co-optimizing the system fuel-and-engine using diesel as an example. It will be clearly shown that the still unused co-optimizing of the system fuel-and-engine (including advanced exhaust after-treatment) as a single entity is a must for enabling cleaner future road transport by cleaner fuels since there are large, still unexploited potentials for improvements in road fuels which will provide major reductions in pollutant emissions both in vehicles already in the field and even more so in future dedicated vehicles.
2007-04-16
Technical Paper
2007-01-0107
Alexander Wäschle
Investigations of the aerodynamic influence of rotating wheels on a simplified vehicle model as well as on a series production car are presented. For this research CFD simulations are used together with wind tunnel measurements like LDV and aerodynamic forces. Several wheel rim geometries are examined in stationary and in rotating condition. A good agreement could be achieved between CFD simulations and wind tunnel measurements. Based on the CFD analysis the major aerodynamic mechanisms at rotating wheels are characterized. The flow topology around the wheels in a wheel arch is revealed. It is shown, that the reduction of drag and lift caused by the wheel rotation on the isolated wheel and the wheel in the wheel arch are based on different effects of the airflow. Though the forces decrease at the front wheel due to the wheel rotation locally, the major change in drag and lift happens directly on the automotive body itself.
2007-04-16
Technical Paper
2007-01-0493
P. Klein, R. Grüter, O. Loffeld
External Exhaust Gas Recirculation, EGR, is a central issue in controlling emissions in up-to-date diesel engines. An empirical model has been developed that calculates the EGR ratio as a function of the engine speed, the engine load and special characteristics of the heat release rate. It was found that three combustion characteristics correlate well with the EGR ratio. These characteristics are the ignition delay, the premixed combustion ratio and the mixing-controlled combustion ratio. The calculation of these characteristics is based on parameter subsets, which were determined using an optimization routine. The model presented was developed based on these optimized characteristics.
2004-03-08
Technical Paper
2004-01-1377
Oliver Moos, Franz R. Klimetzek, Rainer Rossmann
Topology optimization in structural analysis is known for many years. In the presented procedure, “topology optimization” is used for computational fluid dynamics (CFD) for the first time. It offers the possibility of a very fast optimization process under utilization of the physical information in the flow field instead of using optimization algorithms like for example evolution strategies or gradient based methods. This enables the design engineer to generate in a first layout air guiding systems with low pressure drop in a fast and easy manner, which can than be improved further due to constraints of styling or production requirements. This procedure has been tested with many examples and shows promising results with a reduction in pressure loss up to 60% compared to a duct designed in CAD in the traditional way.
2004-03-08
Technical Paper
2004-01-1593
Klaus Lamberg, Michael Beine, Mario Eschmann, Rainer Otterbach, Mirko Conrad, Ines Fey
Permanently increasing software complexity of today's electronic control units (ECUs) makes testing a central and significant task within embedded software development. While new software functions are still being developed or optimized, other functions already undergo certain tests, mostly on module level but also on system and integration level. Testing must be done as early as possible within the automotive development process. Typically ECU software developers test new function modules by stimulating the code with test data and capturing the modules' output behavior to compare it with reference data. This paper presents a new and systematic way of testing embedded software for automotive electronics, called MTest. MTest combines the classical module test with model-based development. The central element of MTest is the classification-tree method, which has originally been developed by the DaimlerChrysler research department.
2004-10-18
Technical Paper
2004-21-0012
Werner Preuschoff
Increasing vehicle complexity, broader vehicle variety, and global vehicle projects are a major challenge to all global vehicle manufacturers. Common vehicle projects not only require a common E/E-architecture in order to share components, but also a common diagnostic strategy. On-board and off-board strategies have been developed to achieve this goal. This paper will explain the importance of ISO-standardization, common networking & diagnostic architectures and standardized access to vehicle electronics. Also the need for a common diagnostic process chain throughout engineering, manufacturing and service, and the need for harmonized vehicle standards between passenger cars and heavy duty trucks will be addressed.
2003-10-27
Technical Paper
2003-01-3109
W. A. Givens, W. H. Buck, A. Jackson, A. Kaldor, A. Hertzberg, W. Moehrmann, S. Mueller-Lunz, N. Pelz, G. Wenninger
After-treatment systems (ATS) consisting of new catalyst technologies and particulate filters will be necessary to meet increasingly stringent global regulations limiting particulate matter (PM) and NOx emissions from heavy duty and light duty diesel vehicles. Fuels and lubes contain elements such as sulfur, phosphorus and ash-forming metals that can adversely impact the efficiency and durability of these systems. Investigations of the impact of lubricant formulation on the transfer of ash-forming elements to diesel particulate filters (DPF) and transfer of sulfur to NOx storage catalysts were conducted using passenger car diesel engine technology. It was observed that for ATS configurations with catalyst(s) upstream of the DPF, transfer of ash-forming elements to the DPF was significantly lower than expected on the basis of oil consumption and lube composition. Sulfur transfer strongly correlated with oil consumption and lubricant sulfur content.
2005-04-11
Technical Paper
2005-01-1097
Jens Franz, Juergen Schmidt, Christof Schoen, Manfred Harperscheid, Stephan Eckhoff, Martin Roesch, Juergen Leyrer
The oil ash accumulation on modern three way catalyst (TWC) as well as its influence on catalyst deactivation is evaluated as a parameter of oil consumption, kind of oil additive compound and additive concentration. The oil ash accumulation is characterized by XRF and SEM/EDX in axial direction and into the washcoat depth of the catalyst. The deposition patterns of Ca, Mg, P and Zn are discussed. The catalytic activity of the vehicle and engine bench aged catalysts is measured by performing model gas tests and vehicle tests, respectively. The influence of oil ash accumulation on the lifetime emission behavior of the vehicle is discussed.
2005-04-11
Technical Paper
2005-01-0750
Hartmut Pohlheim, Mirko Conrad, Arne Griep
Whereas the verification of non-safety-related, embedded software typically focuses on demonstrating that the implementation fulfills its functional requirements, this is not sufficient for safety-relevant systems. In this case, the control software must also meet application-specific safety requirements. Safety requirements typically arise from the application of hazard and/or safety analysis techniques, e.g. FMEA, FTA or SHARD. During the downstream development process it must be shown that these requirements cannot be violated. This can be achieved utilizing different techniques. One way of providing evidence that violations of the safety properties identified cannot occur is to thoroughly test each of the safety requirements. This paper introduces Evolutionary Safety Testing (EST), a fully automated procedure for the safety testing of embedded control software.
2005-04-11
Technical Paper
2005-01-0968
Athanasios G. Konstandopoulos, Nickolas Vlachos, Ioannis Stavropoulos, Sofia Skopa, Uwe Schumacher, Dirk Woiki, Marcus Frey
This paper describes work supporting the development of a new Diesel particulate trap system for heavy duty vehicles based on porous sintered metal materials that exhibit interesting characteristics with respect to ash tolerance. Experimental data characterizing the material (permeability, soot and ash deposit properties) are obtained in a dedicated experimental setup in the side-stream of a modern Diesel engine as well as in an accelerated ash loading rig. System level simulations coupling the new media characteristics to 3-D CFD software for the optimization of complete filter systems are then performed and comparative assessment results of example designs are given.
2004-03-08
Technical Paper
2004-01-0106
R. Steiner, C. Bauer, C. Krüger, F. Otto, U. Maas
A progress variable approach for the 3D-CFD simulation of DI-Diesel combustion is introduced. Considering the Diesel-typical combustion phases of auto-ignition, premixed and diffusion combustion, for each phase, a limited number of characteristic progress variables is defined. By spatial-temporal balancing of these progress variables, the combustion process is described. Embarking on this concept, it is possible to simulate the reaction processes with detailed chemistry schemes. The combustion model is coupled with a mesh-independent Eulerian-spray model in combination with orifice resolving meshes. The comparison between experiment and simulation for various Diesel engines shows good agreement for pressure traces, heat releases and flame structures.
2004-03-08
Technical Paper
2004-01-0669
Gerhard Wickern, Berthold Schwartekopp
In open jet wind tunnels with high blockage ratios a sharp rise in drag is observed for models approaching the nozzle exit plane. The physical background for this rise in drag will be analyzed in the paper. Starting with a basic analysis of the dependencies of the effect on model and wind tunnel properties, the key parameters of the problem will be identified. It will be shown using a momentum balance and potential flow theory that interaction between model and nozzle exit can result in significant tunnel-induced gradients at the model position. In a second step, a CFD-based investigation is used to show the interaction between nozzle exit and a bluff body. The results cover the whole range between open jet and closed wall test section interaction. The model starts at a large distance from the nozzle, then moves towards the nozzle, enters the nozzle and is finally completely inside the nozzle.
2007-10-29
Technical Paper
2007-01-4137
P. Wenzel, R. Steiner, C. Krüger, R. Schießl, C. Hofrath, U. Maas
A chemical sub-model for realistic CFD simulations of Diesel engines is developed and demonstrated by application to some test cases. The model uses a newly developed progress variable approach to incorporate a realistic treatment of chemical reactions into the description of the reactive flow. The progress variable model is based on defining variables that represent the onset and temporal development of chemical reactions before and during self ignition, as well as the stage of the actual combustion. Fundamental aspects of the model, especially its physical motivation and finding a proper progress variable, are discussed, as well as issues of practical implementation. Sample calculations of Diesel-typical combustion scenarios are presented which are based on the progress-variable model, showing the capability of the model to realistically describe the ignition-and combustion phase.
2007-09-16
Technical Paper
2007-24-0044
D. Suzzi, C. Krüger, M. Blessing, P. Wenzel, B. Weigand
The main objective of engine 3D CFD simulation is nowadays the support for combustion design development. New combustion concepts (e.g. Low Temperature Combustion, HCCI, multiple injection strategies …) could be analyzed and predicted through detailed thermodynamical computation. To achieve this aim many simulation tools are needed: each of them has to be capable to reproduce the sensitivities of combustion design parameters through physically based models. The adopted approach consists of the coupling of different models for 3D-nozzle flow, orifice-resolved spray formation in Eulerian coordinates and combustion. The advantages of the method will be proofed on an operative DI-diesel truck engine case, run with different nozzle geometries.
2007-10-30
Technical Paper
2007-01-4289
Mark Alvick, Norm Ritchie, Daniel Schmit, Bruce Koepke, Michal Wozniak, James Chinni, Michael Roelleke, Elvira Diehl
Heavy trucks are produced with a great variety of vehicle configurations, operate over a wide range of gross vehicle weight and sometimes function in extreme duty environments. Frontal crashes of heavy trucks can pose a threat to truck occupants when the vehicle strikes another large object such as bridge works, large natural features or another heavy-duty vehicle. Investigations of heavy truck frontal crashes indicate that the factors listed above all affect the outcome for the driver and the resulting damage to the truck Recently, a new chassis was introduced for on-highway heavy truck models that feature frontal airbag occupant protection. This introduction presented an opportunity to incorporate the knowledge gained from crash investigation into the process for developing the crash sensor's parameter settings.
2007-04-16
Technical Paper
2007-01-1117
A. Güthenke, D. Chatterjee, M. Weibel, N. Waldbüßer, B. Thinschmidt, P. Kočí, M. Marek, M. Kubíček
To fulfill future emission standards for diesel engines, combined after-treatment systems consisting of different catalyst technologies and diesel particulate filters (DPF) are necessary. For designing and optimizing the resulting systems of considerable complexity, effective simulation models of different catalyst and DPF technologies have been developed and integrated into a common simulation environment called ExACT (Exhaust After-treatment Components Toolbox). This publication focuses on a model for the NOx storage and reduction catalyst as a part of that simulation environment. A heterogeneous, spatially one-dimensional (1D), physically and chemically based mathematical model of the catalytic monolith has been developed. A global reaction kinetic approach has been chosen to describe reaction conversions on the washcoat. Reaction kinetic parameters have been evaluated from a series of laboratory experiments.
2007-04-16
Technical Paper
2007-01-1097
Berthold Martin, Hussein Dourra, Charles Redinger, Mark Champine, Fred Goedtel, Gary Lowe, Steve Barrer
A new six-speed transaxle has been introduced by the Chrysler Group of DaimlerChrysler AG. Along with the six forward ratios in the normal upshift sequence, this transaxle features a seventh forward ratio used primarily in a specific downshift sequence. A significant technical challenge in this design was the control of so-called double-swap shifts, the exchange of two shift elements for two other shift elements. In the case at hand, one of the elements is a freewheel. A unique solution is discussed for successful control of double-swap shifts. The new design replaces a four-speed transaxle but makes use of a large percentage of parts and processes from the four-speed design. This approach enabled the new transaxle to reach production in three years from concept. The new transaxle, referred to as the 62TE, has substantially improved performance and passing maneuvers coupled with a new 4.0L high output engine for which the 62TE was developed.
2004-03-08
Technical Paper
2004-01-0445
Alexander Wäschle, Stephane Cyr, Timo Kuthada, Jochen Wiedemann
This paper presents velocity and pressure measurements obtained around an isolated wheel in a rotating and stationary configuration. The flow field was investigated using LDA and a total pressure probe in the model scale wind tunnel at IVK/FKFS. Drag and lift were determined for both configurations as well as for the wheel support only. These results were used as a reference for comparing numerical results obtained from two different CFD codes used in the automotive industry, namely STAR-CD™ and PowerFLOW™. The comparison gives a good overall agreement between the experimental and the simulated data. Both CFD codes show good correlation of the integral forces. The influence of the wheel rotation on drag and lift coefficients is predicted well. All mean flow structures which can be found in the planes measured with LDA can be recognized in the numerical results of both codes. Only small local differences remain, which can be attributed to the different CFD codes.
2004-03-08
Technical Paper
2004-01-1276
S. Eckhoff, W. Mueller, D. Lindner, J. Leyrer, T. Kreuzer, G. Vent, C. Schoen, J. Schmidt, J. Franz
To meet future emission levels the industry is trying to reduce tailpipe emissions by both, engine measures and the development of novel aftertreatment concepts. The present study focuses on a joint development of aftertreatment concepts for gasoline engines that are optimized in terms of the exhaust system design, the catalyst technology and the system costs. The best performing system contains a close-coupled catalyst double brick arrangement using a new high thermal stable catalyst technology with low precious metal loading. This system also shows an increased tolerance against catalyst poisoning by engine oil.
2004-03-08
Technical Paper
2004-01-1057
Frank W. Baumann, Lutz Eckstein
Accident statistics show that rollover accidents contribute to a large proportion of fatal traffic accidents in the U.S.. In the past it has been documented that some light passenger cars showed tendencies to roll over in evasive lane change maneuvers. In 1997, a newly developed mini van rolled over in a severe double lane change test called “moose-test”. Recently (2001), a new SUV showed similar tendencies in the Consumers Union Short Course test. It is not immediately clear why these evasive test maneuvers are so strongly related to untripped rollover of light passenger vehicles. Therefore, the goal of current research is to understand the circumstances and effects causing modern passenger vehicles to roll over in evasive maneuvers on the road. This paper discusses research activities concerning the following questions: How do critical steering strategies lead to untripped rollover? Are resonant frequencies excited during maneuvers leading to rollover?
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