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Application of a method for the estimation of transmissivity of transparent surfaces to exterior lighting applications

Volkswagen AG-Ruben Stahlbaum
  • Technical Paper
  • 2020-01-1197
To be published on 2020-04-14 by SAE International in United States
The paper derives a practical method for analyzing transmission rates for light passing through transparent media like outer lenses of head lamps and tail lamps. It is shown that only two geometric parameters are needed to do the analysis, as are the angle of incidence measured to the surface normal and the surface normal itself. The surface is needed to be described mathematically - whether analytical (CAD) or discretized (FE or CFD), but no thickness is necessary. Two fields of application will be shown. The first one is the estimation of light performance or module position of head lamps in the early design process. A second one adresses the optimal time to doing outdoor weathering tests with respect to maximal impact of solar irradiation
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Virtual Investigation of Real Fuels by Means of 3D-CFD Engine Simulations

Volkswagen AG-Donatus Wichelhaus
FKFS-Francesco Cupo, Marco Chiodi
  • Technical Paper
  • 2019-24-0090
Published 2019-09-09 by SAE International in United States
The reduction of both harmful emissions (CO, HC, NOx, etc.) and gases responsible for greenhouse effects (especially CO2) are mandatory aspects to be considered in the development process of any kind of propulsion concept. Focusing on ICEs, the main development topics are today not only the reduction of harmful emissions, increase of thermodynamic efficiency, etc. but also the decarbonization of fuels which offers the highest potential for the reduction of CO2 emissions. Accordingly, the development of future ICEs will be closely linked to the development of CO2 neutral fuels (e.g. biofuels and e-fuels) as they will be part of a common development process. This implies an increase in development complexity, which needs the support of engine simulations. In this work, the virtual modeling of real fuel behavior is addressed to improve current simulation capabilities in studying how a specific composition can affect the engine performance. The goal is to create a series of models that allow to virtually investigate different fuels and to minimize, as much as possible, the costly and time-consuming experimental tests. In…
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Experimental Investigation of the Droplet Field of a Rotating Vehicle Tyre

Volkswagen AG-Veith Strohbücker, Reinhold Niesner
FKFS, Forschungsinstitut für Kraftfahrwesen und Fahrzeugmoto-Domenik Schramm, Timo Kuthada
Published 2019-06-18 by SAE International in United States
The consideration of vehicle soiling in the development process becomes ever more important because of the increasing customer demands on current vehicles and the increased use of camera and sensor systems due to autonomous driving. In the process of self-soiling, a soil-water mixture is whirled up by the rotation of the car’s own wheels and deposits on the vehicle surface. The validation of the soiling characteristics in vehicle development usually takes place in an experimental manner, but is increasingly supported by numerical simulations.The droplet field at the tyre has been investigated several times in the past. However, there are no published information regarding the physical background of the droplet formation process and the absolute droplet sizes considering the position at the tyre and the behaviour at different velocities. In the numerical self-soiling simulations, this droplet whirl up process is modelled by a non-rotating wheel, where equally sized droplets are injected tangentially from homogenous emitter lines on the tyre surface into the airfield. The impact of the simplifications of this approach on the final result of…
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Experimental and Numerical Analysis of Pre-Chamber Combustion Systems for Lean Burn Gas Engines

Volkswagen AG-Gunesh Tallu, Gwendal Lucas, Michael Weissner
Ricardo UK Ltd-Evgeniy Shapiro, Nick Tiney
Published 2019-04-02 by SAE International in United States
The current trend in automobiles is towards electrical vehicles, but for the most part these vehicles still require an internal combustion engine to provide additional range and flexibility. These engines are under stringent emissions regulations, in particular, for the reduction of CO2. Gas engines which run lean burn combustion systems provide a viable route to these emission reductions, however designing these engines to provide sustainable and controlled combustion under lean conditions at λ=2.0 is challenging. To address this challenge, it is possible to use a scavenged Pre-Chamber Ignition (PCI) system which can deliver favorable conditions for ignition close to the spark plug. The lean charge in the main combustion chamber is then ignited by flame jets emanating from the pre-chamber nozzles. Accurate prediction of flame kernel development and propagation is essential for the analysis of PCI systems. A modelling approach is proposed based on the Dynamic Discrete Particle Ignition Kernel model coupled with the G-equation combustion model. The model is validated for an air/methane academic benchmark. The approach is then applied to the investigation of…
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Investigation of an Innovative Combustion Process for High-Performance Engines and Its Impact on Emissions

Volkswagen AG-Donatus Wichelhaus
FKFS-Marco Chiodi, Andreas Kaechele
Published 2019-01-15 by SAE International in United States
Over the past years, the question as to what may be the powertrain of the future has become ever more apparent. Aiming to improve upon a given technology, the internal combustion engine still offers a number of development paths in order to maintain its position in public and private mobility. In this study, an innovative combustion process is investigated with the goal to further approximate the ideal Otto cycle. Thus far, similar approaches such as Homogeneous Charge Compression Ignition (HCCI) shared the same objective yet were unable to be operated under high load conditions. Highly increased control efforts and excessive mechanical stress on the components are but a few examples of the drawbacks associated with HCCI. The approach employed in this work is the so-called Spark Assisted Compression Ignition (SACI) in combination with a pre-chamber spark plug, enabling short combustion durations even at high dilution levels. This operation mode leads to substantial improvements in terms of fuel consumption up to highest load conditions. Developed in close collaboration with Volkswagen Motorsport and the FKFS, the experimental…
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Trimmed Body Static Stiffness Identification Using Dynamic Measurements: Test Methodology and Correlation with CAE Results

Volkswagen AG-Elmar Teipen
Siemens Industry Software-Simona Anna Ottaiano, Theo Geluk
Published 2018-06-13 by SAE International in United States
A key metric of a car body structure is the body stiffness, which shows significant correlation with different vehicle performance attributes as NVH, comfort and vehicle handling.Typical approaches to identify static stiffness characteristics are the use of a static stiffness test bench or the ‘static-from-dynamic’ approach in which free-free acquired transfer functions are used to build a modal model from which the static stiffness characteristics are extracted. Both of these approaches have limitations, the static stiffness bench with respect to clamping conditions and reproducing those in CAE, the static-from-dynamic with respect to the modal analysis (EMA) that needs to be performed. EMA is a subjective process, which can limit result robustness. In addition, performing EMA on a trimmed body is difficult due to the high modal density and the high level of damping. Strong benefit however of the static-from-dynamic approach is the ability to characterize the body stiffness without need for clamping of the structure.In this paper a robust static-from-dynamic approach is described that allows static stiffness identification not only for Body-in-White but also on…
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Steering Feedback Perception of Average Drivers

Volkswagen AG-Johannes Grau, Bastian Boßdorf-Zimmer
Institute of Automotive Engineering-Jan Hendrik Sterthoff, Roman Henze, Ferit Küçükay
Published 2018-04-15 by SAE International in United States
Electromechanical steering systems (EPS) provide assisting steering force through an electric motor, often paired with a screw drive. The combination of an electric motor and a screw drive lead to high inertia and thus to a reduced feedback of tire force behavior at the steering wheel. This force behavior contains information about driving conditions and road surface. However, the electric motor can be used to actively enhance and manipulate steering feedback. This article describes the driver perception of modified steering feedback. The presented data is collected carrying out a driving simulator study with average drivers as test subjects. In this study the driver experiences a modified steering feedback at a change of road friction coefficient. Based on the test subjects ratings the perception, acceptance and controllability of the presented steering feedback modifications are assessed. Aim of this article is to present the objectivization of subjective ratings and to describe the applicability of modified steering feedback.
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Validating Prototype Connected Vehicle-to-Infrastructure Safety Applications in Real- World Settings

Volkswagen AG-Jan-Niklas Meier
CAMP LLC-Jayendra Parikh
Published 2018-04-03 by SAE International in United States
This paper summarizes the validation of prototype vehicle-to-infrastructure (V2I) safety applications based on Dedicated Short Range Communications (DSRC) in the United States under a cooperative agreement between the Crash Avoidance Metrics Partners LLC (CAMP) and the Federal Highway Administration (FHWA). After consideration of a number of V2I safety applications, Red Light Violation Warning (RLVW), Curve Speed Warning (CSW) and Reduced Speed Zone Warning with Lane Closure Warning (RSZW/LC) were developed, validated and demonstrated using seven different vehicles (six passenger vehicles and one Class 8 truck) leveraging DSRC-based messages from a Road Side Unit (RSU). The developed V2I safety applications were validated for more than 20 distinct scenarios and over 100 test runs using both light- and heavy-duty vehicles over a period of seven months. Subsequently, additional on-road testing of CSW on public roads and RSZW/LC in live work zones were conducted in Southeast Michigan. Application performance analysis revealed that proper and accurate infrastructure maps are crucial for the desired functioning of the V2I safety applications.
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Development of Wireless Message for Vehicle-to-Infrastructure Safety Applications

Volkswagen AG-Jan-Niklas Meier
CAMP LLC-Jayendra Parikh
Published 2018-04-03 by SAE International in United States
This paper summarizes the development of a wireless message from infrastructure-to-vehicle (I2V) for safety applications based on Dedicated Short-Range Communications (DSRC) under a cooperative agreement between the Crash Avoidance Metrics Partners LLC (CAMP) and the Federal Highway Administration (FHWA). During the development of the Curve Speed Warning (CSW) and Reduced Speed Zone Warning with Lane Closure (RSZW/LC) safety applications [1], the Basic Information Message (BIM) was developed to wirelessly transmit infrastructure-centric information. The Traveler Information Message (TIM) structure, as described in the SAE J2735, provides a mechanism for the infrastructure to issue and display in-vehicle signage of various types of advisory and road sign information. This approach, though effective in communicating traffic advisories, is limited by the type of information that can be broadcast from infrastructures. The new BIM provides additional infrastructure data needed to support dynamic vehicles based safety applications and also leverages existing SAE J2735 data elements. By including data containers specific to other applications, the proposed BIM framework can be extended to support additional safety applications without compromising on backward compatibility to…
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Worldwide Electrical Energy Consumption of Various HVAC Systems in BEVs and Their Thermal Management and Assessment

Volkswagen AG-Malte Westerloh, Sven Twenhövel
University of Braunschweig-Juergen Koehler, Walter Schumacher
Published 2018-04-03 by SAE International in United States
Battery electric vehicles (BEVs) are equipped with Mobile Air Conditioning systems (MACs) to ensure a comfortable cabin temperature in all climates and ambient conditions as well as the optional conditioning of the traction battery. An assessment of the global electrical energy consumption of various MACs has been derived, where the basis of the assessment procedure is the climate data GREEN-MAC-LCCP 2007 (Global Refrigerants Energy & Environmental - Mobile Air Condition - Life Cycle Climate Performance) and the improved LCCP2013 (Life Cycle Climate Performance. The percentage driving time during 6 AM and 24 PM is divided into six different temperature bins with the solar radiation and relative humidity for 211 cities distributed over Europe, North, Central, and South America, Asia, South West Pacific, and Africa. The energy consumption of the MACs is determined by a thermal vehicle simulation. In this work, four different MACs are simulated and compared. The MACs that are investigated are two conventional refrigeration cycles with PTC (Positive Thermal Coefficient, one with R-1234yf and the other with R-744 as the refrigerant, as well…
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