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Combination of an NOx storage and reduction catalyst (NSRC, called also lean NOx trap, LNT) and a catalyst for the selective catalytic reduction of NOx by NH₃ (NH₃-SCR) offers a potential to significantly increase the efficiency of NSRC-based exhaust gas aftertreatment systems. Under most situations the SCR catalyst is able to adsorb the NH₃ peaks generated in the NSRC during the regeneration and utilize it for additional NOx reduction in the course of the consequent lean phase. This synergy becomes more important with the aged NSRC, where generally lower NOx conversions and higher NH₃ yields in wider range of operating temperatures are observed (in comparison with the fresh or de-greened NSRC). In this paper we present global kinetic models for the NSRC (Pt/Ba/Ce/gγ-Al₂O₃ catalyst type) and NH₃-SCR (Fe-ZSM5 catalyst type).

Low interior noise levels in combination with a comfortable sound is an important task for passenger cars. Due to the reduction of many noise sources over the last decades, nowadays tire-road noise has become one of the dominant sources for the interior noise. Especially for manufactures of luxury cars, the reduction of tire-road noise is a big challenge and therefore a central part of NVH development. The knowledge of the noise transmission behavior based on the characteristics of the relevant sources is a fundamental of a modern NVH - development process. For tire-road noise the source characteristics can be described by wheel forces and radiated airborne noise. In combination with the related vehicle transfer functions it is possible to describe the noise transmission behavior in detail. A method for estimating wheel forces and radiated airborne noise is presented.

Aero-vibro-acoustic prediction of interior noise associated with exterior flow requires accurate predictions of both fluctuating surface pressures across the exterior of a vehicle and efficient models of the vibro-acoustic transmission of these surface pressures to the interior of a vehicle. The simulation strategy used in this paper combines both CFD and vibro-acoustic methods. An accurate excitation field (which accounts for both hydrodynamic and acoustic pressure fluctuations) is calculated with a hybrid CAA approach based on an incompressible unsteady flow field with an additional acoustic wave equation. To obtain the interior noise level at the driver's ears a vibro-acoustic model is used to calculate the response of the structure and interior cavities. The aero-vibro-acoustic simulation strategy is demonstrated for a Mercedes-Benz S-class and the predictions are compared to experimental wind tunnel measurements.

A powerful and efficient turbocharger turbine benefits the engine in many aspects, such as better transient response, lower NOx emissions and better fuel economy. The turbine performance can be further improved by employing secondary flow injection through an injector over the shroud section. A secondary flow injection system can be integrated with a conventional turbine without affecting its original design parameters, including the rotor, volute, and back disk. In this study, a secondary flow injection system has been developed to fit for an asymmetric twin-scroll turbocharger turbine, which was designed for a 6-cylinder heavy-duty diesel engine, aiming at improving the vehicle’s performance at 1100 rpm under full-loading conditions. The shape of the flow injector is similar to a single-entry volute but can produce the flow angle in both circumferential and meridional directions when the flow leaves the injector and enters the shroud cavity.

A numerical model for a diesel oxidation catalyst (DOC) is presented. It is based on a spatially 1D, physical and chemically based modeling of the relevant processes within the catalytic monolith. A global reaction kinetic approach has been chosen to describe the chemical reactions. Water condensation and evaporation was also considered, in order to predict the cold start behavior. Reaction kinetic parameters have been evaluated from a series of laboratory experiments. A correlation between the kinetic parameters and the noble metal loading was developed. The model was used in combination with a SCR-Model to study the influence of changes of noble metal loading and DOC volume on the overall transient NOx performance of a DOC+DPF+SCR system.

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.

Aerodynamic design and thermal management are some of the most important tasks when developing new concepts for the flow around tractor-trailers. Today, both experimental and numerical studies are an integral part of the aerodynamic and thermal design processes. A variety of studies have been conducted how the aerodynamic design reduces the drag coefficient for fuel efficiency as well as for the construction of radiators to provide cooling on tractor-trailers. However, only a few studies cover the combined effect of the aerodynamic and thermal design on the air temperature of the under hood flow [8, 13, 16, 17, 20]. The objective of this study is to analyze the heat transfer through forced convection for a scaled Cab-over-Engine (CoE) tractor-trailer model with under hood flow. Different design concepts are compared to provide low under hood air temperature and efficient cooling of the sub components.

While the market share for diesel engines for LD vehicles in Europe has grown continuously in the past years, the market share in North America is still negligible. Until now, it has been possible to fulfill the limits for nitrogen oxides (NOx) both in Europe and in North America by engine measures alone, without using an active NOx aftertreatment system. With the introduction of Tier II Bin 8 and Tier II Bin 5 emissions legislation in the US in 2007, most new diesel applications will now require NOx aftertreatment. One of the possible technologies for the reduction of nitrogen oxides in lean exhaust gas is the NOx storage catalyst which has become the generally-accepted choice for engines with gasoline direct injection systems and which is also utilized in the current diesel Bluetec I systems from Daimler. For heavier applications urea-SCR is the preferred technology to fulfill NOx legislation limits.

Diesel engines have a strong contribution to the CO2 reduction in Europe in the past years. To enable these C02 reduction potential to the US market Mercedes Benz developed the BLUETEC technology for light duty diesel engines. The BLUETEC technology contains an optimized diesel engine and combustion system, an aftertreatment system with DOC, DPF and an active SCR catalyst with AdBlue Dosing System and an enhanced ECU functionality and calibration. For fulfilling the world strongest emission limits of the US legislation there have to be solutions developed for the handling of AdBlue under cold climate below -11°C, managing the refilling event, and the onboard diagnostic. To ensure the emission stability over full useful life on high NOx conversions level, intensive testing of the catalyst technology had to be done. In addition there are self learning functionalities for adapting the dosing strategy to ensure the maximum NOx performance.

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.

Beginning in 2010, Daimler's well-known Diesel Sprinter van has to fulfill the new and clearly tighter NOx emission standards of NAFTA10 (EPA, CARB). This requires an integrated approach of further engine optimizations and the implementation of an innovative exhaust aftertreatment technology. The goal was to develop an overall concept which meets simultaneously the tightened emission standards (including OBD limits) and the increasing customer demands of more power and torque without losing the high fuel efficiency of the small and highly efficient 3-liter V6 diesel engine OM642, which already has been installed in the NAFTA07 Sprinter. In the early stages of the concept phase, the most appropriate NOx aftertreatment technology and certification form (engine or vehicle) had to be selected for this specific vehicle class in the van segment with enhanced requirements to durability, economical efficiency and specific driving behavior.

The economic challenges and environmental imperatives facing the trucking and automobile industries today all point to a pressing need to improve fuel efficiency. Due to increasing volatility of fuel supplies, prices and a growing interest in reducing greenhouse gas emissions, fuel efficiency has taken on new urgency. In the long-haul trucking industry this is especially important given the fact that fuel accounts for a significant share of fleet operating costs. To this end Daimler and NAVTEQ have developed a system to improve fuel economy and reduce CO₂ emissions through the integration of digital map data into Advanced Driver Assistance Systems or ADAS. Digital road map attributes, especially road slope have been demonstrated to enable powertrain controls to anticipate road inclination changes and use this information to predictively enhance load management optimization versus the reactive approach afforded by current technology.

Brake system development and testing is spread over vehicle manufacturers, system and component suppliers. Test equipment from different sources, even resulting from different technology generations, different data analysis and report tools - comprising different and sometimes undocumented algorithms - lead to a difficult exchange and analysis of test results and, at the same time, contributes to unwanted test variability. Other studies regarding the test variability brought up that only a unified and unambiguous data format will allow a meaningful and comparative evaluation of these data and only standardization will reveal the actual reasons of test variability. The text at hand illustrates that a substantial part of test variability is caused by a misinterpretation of data and/or by the application of different algorithms.

Mercedes-Benz BlueTEC passenger cars have been on the cutting edge of clean diesel technology since 2006. These BlueTEC vehicles furthermore passed millions of kilometers in the hands of customers. SCR-equipped passenger cars already meet the most stringent exhaust emissions standards in international markets such as the USA, Europe and Japan. Diesel engines with BlueTEC technology also reduce CO₂ emissions and provide the high torque and performance associated with the diesel engine in addition to keeping exhaust emissions at the lowest possible level. Nowadays the requirements for SCR emission concepts are increasing continuously. In fact the emission legislation is getting stricter with the LEVIII emission standards in 2015. Additionally the requirements and effort for on-board diagnosis are increasing year after year. In combination with ambitious CO₂ targets all these issues constitute the further challenges of BlueTEC SCR emission concepts for worldwide markets.

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.

In order to offer a wide range of driving experiences to their customers, original equipment manufacturers implement different driving programs. The driver is capable of manually switching between these programs which alter drivability parameters in the engine control unit. As a result, acceleration forces and gradients are modified, changing the perceived driving experience. Nowadays, drivability is calibrated iteratively through road testing. Hence, the resulting set of parameters incorporated within the engine control unit is strongly dependent on the individual sentiments and decisions of the test engineers. It is shown, that implementing a set of objective criteria offers a way to reduce the influences of personal preferences and sentiments in the drivability calibration process. In combination with the expertise of the test engineers, the desired vehicle behavior can be formalized into a transient set point sequence to give final shape to the acceleration behavior.

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.

In order to reduce fuel consumption in Fuel Cell Electric Vehicles, effective distribution of power demand between Fuel Cell and Battery is required. Energy management strategies can improve fuel economy by meeting power demand efficiently. This paper explains development of various energy management strategies for Fuel Cell Electric Vehicle with Lithium Ion Battery. Drive cycles used for optimization and analysis of the strategies are New European Drive cycles (NEDC), Japanese Drive cycles (JAP1015), City Drive cycles, Highway Drive cycles (FHDS) and Federal Urban Drive cycles (FUDS). All Fuel consumption and ageing calculations are done using backward model implemented in MATLAB/SIMULINK.

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.

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.