20. Internationales Stuttgarter Symposium

Whereas in the past the air quality in metropolitan areas has been in the center of environmental discussions, today global warming and thus reduction of CO2 emissions is the key focus of public interest.

Sustainability is one of the basic principles of the Daimler AG corporate strategy and a benchmark for its success concerning the entire value chain - from suppliers to products. A central aspect of Mercedes-Benz Cars is the “path to zero-emission driving” that merges three paths leading to the future of mobility: the combination of very efficient high-tech internal combustion engines, hybrid models as well as electric drives with battery or fuel cell. The focus to which we have committed through Ambition2039: Building vehicles that are attractive to customers and at the same time achieve the own ambitious and go even beyond the legally prescribed sustainability goals.

In order to keep the global temperature rise within this century below 2°C above preindustrial level, 196 state parties ratified the Paris Agreement in November 2015 [1]. Under this agreement, each country has to determine and plan appropriate measures to mitigate the effects on global warming. The light duty vehicle sector of the European Union has to substantially contribute to these measures since it is responsible for 12% of the total carbon dioxide emissions, which has a main influence on global warming [2].

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Todays’ travelling is a mess. Overcrowded at any transportation mode: in the air, on the road and on rail tracks. Key requirement of end users for passenger and cargo is easy, convenient and affordable in-time door-to-door transportation.

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AKKA ranks as the European leader in engineering consulting and R&D services in the mobility sector. As an innovation accelerator for its clients, AKKA supports leading industry players throughout the life cycle of their products with cutting edge digital technologies. Their R&D department “AKKA Research” is proudly presenting a new internal project.

The topic is inner city delivery also called last mile, implemented in the logistics by purely electric vans, which are equipped with individual bodies for the goods to be transported and have the required battery as part of the body.

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Mankind in 21st century is successfully striving for prosperity and better living conditions. In parallel, we recognize unusual climatic phenomena in everyday life. A climate change can be detected by everybody even without special instruments.

The testing of autonomous passenger transport vehicles has received considerable public attention in recent years [1]. Some of the suppliers present conversion proposals to enable their vehicles to transport goods. At first glance, this proposal appears to be an innovation in logistics.

Virtual simulation is currently playing an important role in the aero development of Lamborghini vehicles and the reasons for it is coherent with the nature of a super sport car. Short development time, high quality, high power/weight ratio, best lap-time, are part of a project definition with high level of complexity and performance that are shaped by a perfect stile and are the expression of extraordinary engineering solution.

ADAMo (Adaptive Digital Aerodynamics for Motorcycles) is a research project guided by Piaggio S.p.A and partially founded by Toscana region. The object was to increase the performance, safety and comfort of a motorcycle by using active aerodynamics devices.

An unobscured view from the vehicle during rainy weather conditions is essential for occupants’ safety and comfort. With the decrease in the time available for vehicle development and testing, it is becoming even more important to control and predict vehicle water management early in the development cycle to avoid undesired soiling effects. To do so, a transient external aerodynamics transient simulation coupled with a discrete particle phase is explored, where rain droplets away from the vehicle are modeled as Lagrangian particles and rain droplets that impact the vehicle are represented through a film model.

While listening to the voice of the customer two major trends regarding Battery Electrical Vehicles (BEV) become obvious and are therefore necessary to focus on. Based on several different sources the demand for a high driving range of the BEV is a quite apparent fact. To give an indication to that conclusion, three sources will be citied here.

By the middle of this decade it is forecast that more than 25% of all new vehicles worldwide will be equipped with an electric drive, half of them fully electric (BEV) or as fuel cell vehicles (FCEV).

Recent developments in vehicle electrification lead to increasing requirements for electrical machines regarding power output and cost-effective manufacturing. Here, the stator is one of the main active electromagnetic subassemblies, offering significant potential to raise total power output. Therefore, recent studies focus on maximizing copper fill factors by enhancing stator-winding technologies or by inventing new manufacturing approaches.

Usually the elastokinematics of a vehicle axle is evaluated and optimized on a specific kinematics and compliance (K&C) test rig by using statically defined load cases. The vehicle is placed on the test rig and clamped at defined points of the body-in-white. According to the state of technology, the body-in-white is attached at different points though.

Current trends and legislative changes like autonomous driving, emission regulations and connected vehicles lead to new challenges and opportunities for the automotive industry. Recent studies showed that customers expect more comfort and consider it as a purchase criterion in manually driven vehicles [1] as well as in autonomous vehicles [2]. In addition, efficiency continues to gain importance to reduce the emissions of vehicles with internal combustion engines and to increase the range of battery electric and hybrid vehicles [3].

In the age of autonomous driving, car manufacturers have to consider completely new aspects in their vehicle development processes. An important aspect is the understanding of the sensation and perception of vehicle motions by the passengers. Here the target for all automobile manufacturers is similar, providing a confidence-inspiring driving experience.

Measures to improve the efficiency of internal combustion engine driven vehicles such as downsizing- and downspeeding can lead to unwanted side effects such as higher torque excitations by the drive unit. Also future hybrid drive train topologies and new operation modes as a result of hybridization and ongoing change in mobility lead to changed and new excitations. The simultaneously increasing demands for comfort by the customer make new measures to reduce vibrations necessary in modern drive trains.

The adequate dimensioning of drive train components such as gearbox, clutch and drive shaft presents a major technical task. The one of manual transmissions represents a special significance due to the customer’s ability of inducing high force, torque and thermic energy into the powertrain through direct mechanical interconnection of gearstick, clutch pedal and gearbox. Out of this, the question about how to capture the behavior and strain of the components during real operation, as well as their objective evaluation evolves.

Electric vehicles (EVs) are inherently quiet as there is no combustion engine, which is the primary source of noise and vibration in ICE powered vehicles. Therefore, transmissions fitted into EVs are perceived to be noisier than their ICE powered counterparts. Moreover, current EV concepts typically use high rotational speeds to satisfy the power demand, which results in a very large range of excitation frequencies and often produces significant tonal contributions in the emitted noise, which are perceived as particularly unpleasant.

The usage of algorithms to enhance the efficiency of big data processing has found its way into several industrial sectors, including the automotive industry.

Due to the increasing amount of electrification of passenger vehicles, the internal combustion engine (ICE) faces longer switch-off phases. During these periods, the exhaust gas aftertreatment (EAT) components cool down and are not able to convert emissions instantly into harmless gasses when the ICE is turned on again. Since the EAT components only work reliably in a certain temperature range, positioning single EAT-components upstream of the turbine can decrease the time until the light-off temperature is reached.

Der dieselmotorische Antrieb wird auch zukünftig nach Meinung von Experten eine wesentliche Antriebsquelle der individuellen Mobilität darstellen. Vor dem Hintergrund des hohen Wirkungsgrads und der damit einhergehenden noch weiter sinkenden Abgastemperaturen ist die Herausforderung weiter gestiegen, die Abgasnachbehandlung in Richtung zukünftiger „Near-Zero-Emissions“ Ziele zu optimieren. Der Fokus liegt auf der Vorstellung eines neuartigen Abgasreinigungskonzeptes für dieselmotorische Pkw-Antriebe, das die Einhaltung zukünftiger Emissionsgrenzwerte im realen, insbesondere urbanen Fahrbetrieb, sicher und stabil ermöglicht.

Road safety and environmental protection are major concerns of today’s world. These social changes are leading to new technologies and regulations in the automotive sector. Automatization and electrification of vehicles are intended to reduce traffic accidents and emissions.

The number and complexity of driving assistance functions has risen drastically during the last years, electronics are getting more and more important and, in succession, software topics are one of the main drivers for successful automotive development projects. In general, automotive development processes include three important steps: the specification of the function, its implementation and testing. For classical assistance systems, the definition of the functional behavior within those steps could be achieved by defining the possible inputs, the resulting expected outputs and the environment description in form of sensor data. In contrast, particularly the complexity of automated driving functions (ADF) requires more sophisticated description methods.

Endurance testing is one of the final vehicle development steps before a vehicle is approved for mass production and is released to the worldwide markets. At Mercedes-Benz, this is one of the most important testing activities that ensure the highest quality standards and guarantee customer satisfaction. During the endurance testing phase, a fleet of vehicles is driven in a multitude of different driving profiles in different testing locations all around the world, on both public roads and proving grounds.

Artificial Intelligence (AI) offers great potential for ADAS, not only for the enhancement of core functionality, but also for huge improvements of the user interface by using speech or gesture recognition.

Precise information about the course of the lane is an essential prerequisite for driver assistance systems and autonomous driving. The lane is not only necessary for comfortable lateral guidance as described in [1]. Rather, it serves as a reference point for further driving maneuvers such as lane change assistance or the calculation of alternative trajectories [2].

Full validation of the safety of an autonomous vehicle requires excessive amounts of testing and driving hours, which is impossible to achieve without virtual simulations. Therefore, companies seek efficient and smart testing strategies to virtually validate the safety of autonomous vehicle functions aiming to achieve lower costs and less time to market. Simulation-based testing for autonomous and connected vehicles is essential for the future generation of transportation systems.

Modern vehicles come with various advanced driving assistance systems. Today, most of these systems are targeted at improving safety, because human error is a major cause for accidents. Most human errors are related to impaired cognitive processing due to sleepiness, alcohol intoxication or engagement in secondary tasks such as cell phone use that distract from the driving task.

Vehicle development is affected by several fundamental influences. The climate debate leads to an extensive change concerning the drive technology [1]. Furthermore, the OEMs offer a wide range of optional equipment that affects the driving behavior of the vehicle. Examples are chassis control systems, several wheel/tire combinations and different chassis variants.

The control of the driver’s hand torque of an electric power steering system has been state of the art for years. However, due to nonlinear spring characteristics, gear ratios and degrees of freedom that are unconsidered in the design model for the controller resp. observer design, the challenge still lies in the robust implementation of this control approach.

The engine development process today faces the challenge of reducing development time and costs, together with emissions and consumption, but at the same time there is the need to evaluate more and more configurations. The drive lines are imposed by the new RDE legislations, together with the fleet consumption targets to be respected. Assumed so, the virtual development of new engine concepts becomes essential to respect these constraints.

Small natural gas cogeneration engines usually operate with lean mixture and late combustion phasing to comply with NOx emission standards, leading to significant losses in engine efficiency. Refeeding condensed water from the exhaust into the engine in form of a fine spray offers a synergetic possibility for those systems. In fact, it allows an additional exhaust heat recovery.

This study focuses on the comparison of oil lubricated and dry lubricated pistons and their influence on the combustion process of free-piston engine with an opposed piston combustion chamber. The free-piston engine, which is developed by the German Aerospace Centre, works with a two-stroke principle and the dry lubrication is designed to eliminate the pollution caused by traditional oil lubrication in engines with scavenging ports.

Facing a severe climate change due to use of fossil fuels as energy source for the prime movers in industry and transportation, immediate actions to limit global warming to under 2°C are necessary. As the transportation sector is one of the major sources for greenhouse gases, one of the most promising actions to reduce its impact is the transition from internal combustion engines to battery electric vehicles. The European CO2-emmision target supports this transition.

The power industry has to face several challenges regarding energy production and distribution, especially due to the rapid expansion of renewable energies, reduction of base-load thermal power plants, and an increasing fleet of battery electric vehicles. Discussing the challenges of battery electric vehicle charging, it is often ignored that even today these vehicles can be utilized as an adjustable load. And the quality of the energy supply can be measured by anyone checking grid voltages and grid frequency.

From the view of the energy provider integration of e-mobility into smart grid is important, which includes effective dynamic load management and the use of the HVBatteries in the vehicles to store and feedback energy. The user expects sufficient and reliable charging points to recharge his electric vehicle everywhere and at any time.

Based on a Plugin Hybrid Electric Vehicle (PHEV) a new concept for measuring fuel consumption in a real drive situation is presented. The concept uses flow, density, temperature and pressure sensors which contribute to a physical model working in the flow sensor to correct the dominant systematic measurement deviations. The PHEV vehicle is the ideal platform for the demonstration and validation of such model based approach.

In modern vehicle power trains for passenger cars combustion engines will be supplemented more and more by electric engines. However NOx- and particle emissions as well as CO2-emissions by fuel consumption are still in focus. Further progress may be realised by friction reduction as well as by improved mixture preparation and combustion of the fuel.

The potential of ceramic matrix composites in a diversity of applications is being researched. High load brake disks have proven to be a successful adaptation of the materials properties for an automotive system. The paper summarizes the first steps towards the possibility of piston rings made from a ceramic matrix composite.

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The new European emission standard defines that the fleet-average CO2 emission of cars and vans shall not exceed 61.75 g CO2 / km from 2030 onwards [1]. From current point of view, these CO2 emission limits cannot be achieved by vehicle fleets, which are driven by conventional combustion engines only. As a result, hybridized powertrain systems such as plug-in hybrid electric vehicles (PHEVs) are promising technologies, since periods of fully electric driving are considered with 0 g CO2 emission in a tank-to-wheel balance.

In the framework of the “New Vehicle and System Technologies” technical programme funded by the German Federal Ministry of Economic Affairs and Energy, methyl-ether based fuels (DME/OME1) were investigated in the “XME Diesel” project in order to study their potential of being sustainable fuel replacements for diesel engine applications in passenger cars and commercial vehicles. In studies, which covered research activities from fundamental spray investigations over single- and multi-cylinder testing up to vehicle demonstrators, the new fuels were studied with regard to emission formation, efficiency and compatibility to conventional diesel engine technology. Here, promising findings regarding emission reduction (soot-free combustion and reduction of nitrogen oxides) and increased efficiency could be obtained. For the first time, a heavy-duty OME1 based full engine was developed in which the emission-reducing potential of methyl ethers could be demonstrated.