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Technical Paper

μAFS High Resolution ADB/AFS Solution

A cooperation of several research partners supported by the German Federal Ministry of Research and Education proposes a new active matrix LED light source. A multi pixel flip chip LED array is directly mounted to an active driver IC. A total of 1024 pixel can be individually addressed through a serial data bus. Several of these units are integrated in a prototype headlamp to enable advanced light distribution patterns in an evaluation vehicle.
Technical Paper

Wall Heat Transfer in a Multi-Link Extended Expansion SI-Engine

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.
Technical Paper

Virtual Transfer Path Analysis at Daimler Trucks

As for passenger cars, the overall noise and vibration comfort in commercial trucks and busses becomes an increasingly important sales argument. In order to effectively reduce the noise and vibration levels it is required to identify possible NVH issues at an early stage in the vehicle development process. For this reason a so-called “Virtual Transfer Path Analysis” (VTPA) method has been implemented which combines the results obtained from the conventional multi-body simulation and finite element method approaches. The resulting VTPA tool enables Daimler Trucks to systematically investigate and predict the complex interaction between powertrain excitation and the resulting vehicle response well before hardware prototypes become available. An overview of the theory is presented as well as the practical application and outcome of the technique applied in a past product development.
Journal Article

Validation and Sensitivity Studies for SAE J2601, the Light Duty Vehicle Hydrogen Fueling Standard

The worldwide automotive industry is currently preparing for a market introduction of hydrogen-fueled powertrains. These powertrains in fuel cell electric vehicles (FCEVs) offer many advantages: high efficiency, zero tailpipe emissions, reduced greenhouse gas footprint, and use of domestic and renewable energy sources. To realize these benefits, hydrogen vehicles must be competitive with conventional vehicles with regards to fueling time and vehicle range. A key to maximizing the vehicle's driving range is to ensure that the fueling process achieves a complete fill to the rated Compressed Hydrogen Storage System (CHSS) capacity. An optimal process will safely transfer the maximum amount of hydrogen to the vehicle in the shortest amount of time, while staying within the prescribed pressure, temperature, and density limits. The SAE J2601 light duty vehicle fueling standard has been developed to meet these performance objectives under all practical conditions.
Technical Paper

Utilizing Automated Report Generation and Data Acquisition Tools to Guide Fuel Cell Vehicle Fleet Operations

Daimler is an industry leader in the development and deployment of fuel cell vehicles. With more than 100 fuel cell vehicles being driven worldwide at locations including the U.S., Singapore, Japan, Europe, China, and Australia, Daimler currently operates the world's largest fuel cell vehicle fleet. Each fuel cell vehicle is equipped with a powerful telematics system that records a diverse set of vehicle operation and fuel cell specific data for development purposes. Through innovative analysis methods Daimler is gaining unique insight into the technical, environmental, societal, and logistic influences impacting the future of fuel cell vehicle technology.
Technical Paper

Using Timing Analysis for Evaluating Communication Behavior and Network Topologies in an Early Design Phase of Automotive Electric/Electronic Architectures

The increasing functionality and complexity of future electric/electronic architectures requires efficient methods and tools to support design decisions, which are taken in early development phases 6. For the past four years, a holistic approach for architecture development has been established at Mercedes-Benz Cars R&D department. At its core is a seamless design flow, including the conception, the analysis and the documentation for electric/electronic architectures. One of the actual challenges in the design of electric/electronic architectures concerns communication behavior and network topologies. The increasing data exchange between the ECUs creates high requirements for the networks. With the introduction of FlexRay 21 and Ethernet the automotive network architecture become a lot more heterogeneous. Especially gateways must fulfill many new requirements to handle the strict periodic schedule of FlexRay and the partly event-triggered communication on CAN-busses 23.
Technical Paper

Using Simulation to Verify Diagnosis Algorithms of Electronic Systems

In modern vehicles the architecture of electronics is growing more and more complex because both the number of electronic functions – e.g. implemented as software modules – as well as the level of networking between electronic control units (ECUs) is steadily increasing. This complexity leads to greater propagation of failure symptoms, and diagnosing the causes of failure becomes a new challenge. Diagnostics aims at detecting failures such as defect sensors or faulty communication messages. It is subdivided into diagnosis algorithms on an ECU and algorithms running offboard, e.g. on a diagnostic tester. These algorithms have to complement each other in the best possible way. While in the past the diagnosis algorithm was developed late in the development process, nowadays there are efforts to start the development of such algorithms earlier – at least in parallel to developing a new feature itself. This would allow developers to verify the diagnosis algorithms in early design stages.
Technical Paper

Using High-Fidelity Multibody Vehicle Models in Real-Time Simulations

Digital or virtual prototyping by means of a multibody simulation model (MBS) is a standard part of the automotive design process. A high-fidelity model is built and often correlated against test data to increase its accuracy. Once built the MBS model can then be used for high fidelity analysis in ride comfort, handling as well as durability. Next to the MBS model, current industry practice is to develop a reduced degree of freedom model for the design and validation of control or intelligent systems. The models used in the control system design are required to execute in hardware-in-the-loop (HIL) simulations where it is necessary to run real-time. The reason for the creation of the reduced degree of freedom models so far has been that the high-fidelity or off-line model does not execute fast enough to be used in an HIL simulation.
Journal Article

Use of an Eulerian/Lagrangian Framework to Improve the Air Intake System of an Automobile with Respect to Snow Ingress

A simulation approach to predict the amount of snow which is penetrating into the air filter of the vehicle’s engine is important for the automotive industry. The objective of our work was to predict the snow ingress based on an Eulerian/Lagrangian approach within a commercial CFD-software and to compare the simulation results to measurements in order to confirm our simulation approach. An additional objective was to use the simulation approach to improve the air intake system of an automobile. The measurements were performed on two test sites. On the one hand we made measurements on a natural test area in Sweden to reproduce real driving scenarios and thereby confirm our simulation approach. On the other hand the simulation results of the improved air intake system were compared to measurements, which were carried out in a climatic wind tunnel in Stuttgart.
Technical Paper

Towards an Aspect Driven Approach for the Analysis, Evaluation and Optimization of Safety Within the Automotive Industry

An approach will be presented how development projects for safety-related and software-intensive automotive systems can be controlled through the application of model-based risk assessment. Therefore specific control measures have to be developed, which represent the degree of fulfilment of several aspects of safety-related developments. The control measures are evaluated through the analysis of risk-reducing aspects, for which the process of identification and specification is described. Thus, a framework for the creation of a probabilistic and aspect-oriented risk-analysis model (AORA) for safety related projects within automotive industries is currently under development. With respect to the upcoming safety standard ISO 26262 the twofold approach focuses on both, the identification and specification of risk-reducing aspects within the development as well as the application of a probabilistic reasoning model.
Journal Article

Tire Mark Analysis of a Modern Passenger Vehicle with Respect to Tire Variation, Tire Pressure and Chassis Control Systems

Tire mark analysis is an important factor in accident reconstruction. A precise determination of pre- and postcrash speeds as well as longitudinal and lateral accelerations from tire marks contributes significantly to a reliable accident reconstruction. Continuous advancements in tire and vehicle technology – in particular with respect to modern control systems such as anti-lock braking systems (ABS) – raises the question what role tire marks play in accident reconstruction today. Moreover, this accompanies the question to what extent potential interventions by vehicle control systems such as the electronic stability program (ESP®) resp. the electronic stability control (ESC) can be identified in a tire mark. The widespread use of these systems today makes them increasingly important in accident reconstruction.
Technical Paper

The Truck of the Future: Autonomous and Connected Driving at Daimler Trucks

Due to the continuous increasing highway transport and the decreasing investments into infrastructure a better usage of the installed infrastructure is indispensable. Therefore the operation and interoperation of assistance and telematics systems become more and more necessary. Regarding these facts Highway Pilot was developed at Daimler Trucks. The Highway Pilot System moves the truck highly automated and independent from other road users within the allowed speed range and the required security distance. Daimler Trucks owns diverse permissions in Germany and the USA for testing these technologies on public roads. Next generation is the Highway Pilot Connect System that connects three highly automated driving trucks. The connection is established via Vehicle-to-Vehicle communication (V2V).
Technical Paper

The Role of Mercedes Benz do Brasil in the Global Production Network of Daimler Trucks - Based on a Nationalization Project

The commercial vehicle division of Daimler AG developed in the last decades a strong production network, driving the company to a large exchange of parts and aggregates, especially between the plants in Europe and South America. In this article the decision taking methodology for new investments inside this production network is described. The industrialization of engine core parts in Brazil was analyzed by the support of an evaluation tool, and considering the major aspects of a new production site and its supply relationships. The results of the evaluation give transparency about the feasibility of different production network configurations, their interdependencies and the impact of the main influencing factors and drove the board of management to a clear decision, as it happened in other projects which used the same methodology.
Journal Article

The NH3 Inhibition Effect in the Standard SCR Reaction over a Commercial Fe-zeolite Catalyst for Diesel Exhaust Aftertreatment: An Experimental and Modeling Study

Transient and steady-state kinetic data are herein presented to analyze the inhibiting effect of ammonia on the NH₃-SCR of NO at low temperatures over a Fe-zeolite commercial catalyst for vehicles. It is shown that in SCR converter models a rate expression accounting for NH₃ inhibition of the Standard SCR reaction is needed in order to predict the specific dynamics observed both in lab-scale and in engine test bench runs upon switching on and off the ammonia feed. Two redox, dual site kinetic models are developed which ascribe such inhibition to the spill-over of ammonia from its adsorption sites, associated with the zeolite, to the redox sites, associated with the Fe promoter. Better agreement both with lab-scale intrinsic kinetic runs and with engine test-bench data, particularly during transients associated with dosing of ammonia to the SCR catalyst, is obtained assuming slow migration of NH₃ between the two sites.
Technical Paper

The Effect of Pre-Crash Safety Systems to Occupant Protection in Offset Frontal Impacts

The ASSESS project is a European Commission co-funded project that aimed to develop harmonized and standardized assessment procedures for collision mitigation and avoidance systems. ASSESS was one of the first European projects which dealt in depth with the concept of integrated safety, defining methodologies to analyse vehicle safety from a global point of view. As such, the developed procedures included driver behaviour evaluation, pre-crash and crash system performance evaluation and socio-economic assessment. The activities performed for the crash evaluation focussed on the influence of braking manoeuvres in occupant positioning through dynamic braking manoeuvres with real occupants and Madymo and LS-Dyna simulations. The assessment of the passive safety protection level according to the results of the influence of the active systems is based on sled testing and full vehicle testing.
Journal Article

TPA and NVH Prognosis - Application to Mercedes Benz Car Development of New Hybrid Methods Coupling Digital Simulation with Prototype Testing Results

Digital NVH development has become a common tool for any acoustic engineer. Vehicles in their early development stages are nowadays mainly described and validated as digital models. However there still remain needs for improvement in the domains of acoustic and vibration prediction, as instance: refining models, addressing intricate systems, and CAE resistant phenomena. In a background of increasing modularity and process transfers, hybrid methods coupling with testing results, have shown a great potential for improving the quality of NVH prognosis and development quality. Mercedes-Benz passenger car division has developed, tested and introduced a new engineering tool, based on the classical TPA applications coupled with hybrid simulation techniques. This toolbox is used to enhance the prognoses of acoustic interior noise and vibration comfort.
Technical Paper

Stoichiometric Natural Gas Combustion in a Single Cylinder SI Engine and Impact of Charge Dilution by Means of EGR

In this paper experimental results of a medium duty single cylinder research engine with spark ignition are presented. The engine was operated with stoichiometric natural gas combustion and additional charge dilution by means of external and cooled exhaust gas recirculation (EGR). The first part of this work considers the benefits of cooled EGR on thermo-mechanical stress of the engine including exhaust gas temperature, cylinder head temperature, and knock behaviour. This is followed by the analysis of the influence of cooled EGR on the heat release rate. In this context the impact of fuel gas composition is also under investigation. The influence of increasing EGR on fuel efficiency, which is caused by a changed combustion process due to higher fractions of inert gases, is shown in this section. By application of different pistons a relationship between the piston bowl geometry and the flame propagation has been demonstrated.
Technical Paper

Steady-State Experimental and Meanline Study of an Asymmetric Twin-Scroll Turbine at Full and Unequal and Partial Admission Conditions

The use of twin-scroll turbocharger turbines has gained popularity in recent years. The main reason is its capability of isolating and preserving pulsating exhaust flow from engine cylinders of adjacent firing order, hence enabling more efficient pulse turbocharging. Asymmetrical twin-scroll turbines have been used to realize high pressure exhaust gas recirculation (EGR) using only one scroll while designing the other scroll for optimal scavenging. This research is based on a production asymmetrical turbocharger turbine designed for a heavy duty truck engine of Daimler AG. Even though there are number of studies on symmetrical twin entry scroll performance, a comprehensive modeling tool for asymmetrical twin-scroll turbines is yet to be found. This is particularly true for a meanline model, which is often used during the turbine preliminary design stage.
Technical Paper

Standards for Electric/Electronic Components and Architectures

To fulfil the increasing requirements of electric/electronic architectures in automotive environments new concepts for future Electronic Control Units (ECU) are needed. Novel architectures offer much higher potential in terms of performance compared to higher clock rates in standard microcontroller devices. The following contribution discusses the performance benefits of new concepts as well as advantages in early development phases. We focus on two systems: A central body controller and a gateway system. Both are realized on reconfigurable hardware. In comparison to microcontrollers the FPGA technology offers the opportunity of task parallelization and partial dynamically reconfiguration. These novel architectures demand new tool flows and standards which will be also addressed in this paper.
Technical Paper

Standardization of Wiring Harness Data Formats between Truck OEMs and Suppliers

The continuously integration of electrics and electronics (EE) in the last decades is one of the main key drivers for innovation and business success of the Automotive OEMs. This is also applicable for truck manufacturers. On the other side factors like the rising vehicle complexity, number of variants and the warranty costs for EE issues are increasing the pressure on the engineering teams responsible for the mechatronic systems. To address these issues one of the key activities in the European market (focus on Germany) during the last decade was to introduce industry-wide standards for the data transfer of wiring harness data between OEM and harness supplier. In this paper the benefits and technical background of using the standards KBL and KOMP formats within the MB-Trucks brand will be presented. Moreover the role of the Information Technology (IT) will be explained in detail.