21. Internationales Stuttgarter Symposium

Table of Contents

1. Hybrid I

   1. Frontmatter

   2. Active Output Selection for an HEV Boost Maneuver

      Adrian Prochaska, Julien Pillas, Bernard Bäker

      Zusammenfassung

      This paper presents the first real world application of an active output selection strategy, which selects the leading model based on a normalized model quality criterion. The strategy is compared to two other baselines. The algorithm identifies three models of static criteria, which are used for the drivability calibration of the boost maneuver of an 48V HEV. The driving maneuvers are conducted on a powertrain test bench. To validate the results, the experiments were conducted for multiple times. The results confirm analyses on generic toy examples, which indicated great advantages of this learning strategy. In this application example, the strategy saves an amount of 20–65% measurements, depending on which baseline is referenced.

   3. ZF Vision EVplus – the New Definition of Plugin Hybrids

      Michael Ebenhoch, Christoph Schill

      Abstract

      Pragmatically, the ZF vision EVplus is a good solution to close the gap between flexibility, infrastructure, costs and CO₂ efficiency. This concept is based on classic plugin hybrid technology with a stronger shift towards an electric vehicle. The primary drivetrain would be the electric one with an electric range of 80 km - enough for everyday mobility. The rare long-distance use cases can be supported by an efficient combustion engine. With this mix of energy sources, it is possible to generate the best of both. Charging infrastructure can be focused on everyday mobility. CO₂ emissions over lifetime can be optimized by a high rate of electric driven distances with less battery capacity than necessary for long-range battery electric vehicles. ZF Friedrichshafen AG develops not only pure electric drivetrain solutions but also a sustainable and powerful plugin hybrid solution for EVplus: The 8HP 4^th generation. This modular plugin hybrid transmission kit with over 150 kW electric power can cover the requirements of the vision EVplus. The modular approach with mild hybrid and conventional usage ensure high cost efficiency. The fully integrated solution includes the Power Inverter Module as well and fits into standard vehicle architecture.

   4. Holistic Optimization of Energy Consumption of a Hybrid Powertrain with an “Equivalent Fuel Consumption Minimization Strategy” Algorithm

      Michael Zagun

      Abstract

      Modern hybrid powertrains consist of several energy storage and energy converters and allow multiple operating modes to propel a vehicle. In the context of energy management these operating modes are crucial for the consumption of fossil fuel and the recuperation of kinetic energy. A supervisory control strategy is mandatory to meet the driver expectations and to control the energy flow in an efficient manner. Their applicability should cover all possible driving maneuvers, respect component limits and minimize fossil fuel consumption. The “Equivalent Consumption Minimization Strategy” algorithm, as a local optimal control strategy, is derived from literature and applied to a holistic system simulation model of a hybrid powertrain and a thermal management system in the form of an embedded supervisory controller. The objective is to minimize fossil fuel consumption and to include the response dynamics and the thermal effects of the underlying components and subsystems. A special attention is given to the formulation of the cost function which includes three modifications to the well-known [1] equivalent consumption equation. The derived optimal control strategy and the simulation results of the system model are discussed regarding their applicability and the resulting energy economy to an a priori known maneuver. The proposed modifications and extensions prove their applicability in the virtual test environment and recommend themselves for the utilization in further application areas.

2. Test III

   1. Frontmatter

   2. Virtual Validation of Autonomous Driving Functions in Urban Areas with Mixed Traffic

      K. Schreiner, Caroline Handel, M. Obstbaum, F. Beutenmüller, L. Morich, M. Langer, M. Harth

      Abstract

      The mixed operation between motorized and non-motorized, as well as (partially) autonomous and non-autonomous traffic participants represents a major challenge for a reliable operation of automated and autonomous vehicles. How do road users behave towards autonomous vehicles and which environmental elements (static and dynamic) are relevant for the automated vehicle to interpret the current situation? How can the highest level of road safety be guaranteed? These and other questions cannot be verified and validated by real-world test drives alone, but instead must be answered extensively with the help of simulations.

      This publication outlines the state-of-the-art of the virtual validation of automated driving functions placing a focus on environment modelling, scenario generation, as well as traffic and driving simulations in urban contexts. The creation of a photorealistic 3D representation of a district in the city of Ingolstadt using high-precision laser scanners and OpenDRIVE maps is described. Furthermore, the generation of test scenarios using the open standard OpenSCENARIO and coupling of the traffic simulator SUMO with the microscopic and submicroscopic vehicle and environment simulation in Tronis® is presented.

   3. Systematic Validation for Automated Driving

      Christof Ebert, Michael Weyrich, Benjamin Lindemann

      Abstract

      Automated and connected driving up to autonomous vehicles is increasingly being deployed. But the public distrust in their reliability is growing and thus concerns on deployment. The underlying algorithms are not transparent, fast changing and easy to manipulate [1,3,8].

   4. Virtual Verification of Cause-Effect Chains in Automotive Cyber-Physical Systems

      Ricardo Gonzalez de Oliveira, Indrasen Raghupatruni, Arne Hamann, Achim Henkel

      Zusammenfassung

      The technical complexity of automotive Cyber-Physical Systems (CPS) traditionally demands high development and validation efforts. Due to the new technologies entering the automotive market, such as Highly Automated Driving (HAD) (\(\ge \) SAE L3) and connected infotainment, the overall system complexity is currently increasing significantly, challenging traditional system development methods and requiring new approaches for validation and verification (V&V). In parallel, new Electric/Electronic (E/E) architecture patterns are emerging in the automotive industry, distributing the functionalities across several multi-core Electrical Control Units (ECU) connected via Ethernet-based in-vehicle networks. This distributed approach leads to complex inter- and intra-ECU timing relations challenging the concept of freedom from interference according to the ISO 26262, and adding another dimension of effects analysis during V&V in the context of ISO PAS 21448 and the upcoming ISO TR 4804. This work enhances a cyber-physical functional simulation tool to include timing effects in distributed cause-effect chains and multi-technology-communication networks (incl. Ethernet and CAN). The resulting simulation allows the system designer to evaluate the impact of timing properties on a given distributed vehicle function, enabling an early validation of the system, avoiding rework during later stages of the development process resulting from wrong design choices.

3. Pollutants II

   1. Frontmatter

   2. The Increasing Importance of Particles, Volatile Organic Compounds and Ammonia in Future Emissions Regulation

      Nick Molden, James Hobday

      Abstract

      Ensuring continuing environmental and health improvements, it is important regularly to reassess what pollutants from vehicles are targeted. Are the right compounds being regulated? The Emissions Analytics’ presentation looks at a range of pollutant sources that may need to be considered to give a holistic view of the environmental impact of vehicles, supported by data from its independent, real-world EQUA test programme.

      • Post-Euro-6 emissions regulation in Europe is an opportunity to simplify and refocus on emerging environment threats.
      • Certain unregulated tailpipe pollutants, such as ammonia, which contributes to secondary particle formation, are candidates for future regulation.
      • Volatile organic compounds are of interest from several angles: vehicle interior air quality and the off-gassing from materials; tailpipe speciation of hydrocarbons including formaldehyde; and off-gassing from tyres.
      • Tyre wear emissions are currently unregulated but are believed to be a growing contributor to air and marine pollution.
      • Emissions Analytics runs independent test programmes that investigate and quantify real-world exhaust, cabin and tyre pollution. Resulting measurements form the EQUA Index database, which is the source of results presented in this paper.

   3. Denoxtronic 8 by Bosch – Next Step in Evolution for Commercial Vehicles and Off-Road

      Erik Weingarten, Dirk Samuelsen, Werner Christl, Nicolas Ide

      Abstract

      The diesel engine plays an essential role offering competitive total cost of ownership and in reducing CO₂ for manufacturers (OEM) of commercial vehicles and off-road applications - and it will continue to do so in the next years in the context of increasing diversity in the powertrain mix striving for carbon neutrality in the near decades to come.

      Requirements regarding NO_x emissions have been and will remain a major driver for further development of this technology and complying with these requirements will induce further actions on the engine and the exhaust system. SCR-based exhaust-gas treatment (EGT) is the method of choice to support OEMs in achieving future emission requirements.

      For Bosch, a double injection SCR with closed-loop control based on adequate EGT sensors represents an efficient, robust and targeted method to achieve this goal. As a major part of the SCR system the urea dosing system needs to provide adequate and precise dosing rates to ensure the efficiency of the NOx conversion. Taking On Board Diagnostics requirements into account, not only low dosing tolerances are important, but also an accurate monitoring of potential deviations. In this paper, the key drivers for a new dosing system “Denoxtronic 8” are presented. In the course of developing this optimized system, Bosch profited from years of EGT domain experience and succeeded in implementing newly designed Big Data Analysis methods helping to master the rising numbers of requirements.

   4. Investigation of LNT Regeneration Strategy for Diesel Engines with High Internal Residual Gas Rates

      Markus Maul, Michael Brotz, Michael Grill, Michael Bargende

      Abstract

      A diesel engine with a Lean NO_x Trap (LNT) operates alternating in lean and rich mode. In lean mode, the LNT stores the emitted nitrogen oxide emissions (NO_x). In rich mode, the engine produces large amounts of carbon monoxide (CO), hydrogen (H₂), and hydrocarbons (HC), which reduces the stored NO_x in the LNT. Law restricts NO_x, CO, and HC emissions. The aim is a low level of these emitters, but they can pass through the LNT. The right timing of lean and rich mode can help to reduce NO_x emissions with acceptable CO emissions. A variable valve lift system (VVT), which generates high internal residual gas rates, is considered to extend the operation range in which regeneration is possible. The present work deals with investigating regeneration-timing influences and developing an LNT regeneration strategy for real-driving-emission (RDE) simulation. Used this strategy, the VVT system’s potential is evaluated.

4. Reports from FVV Projects

   1. Frontmatter

   2. CNG-DI-Engine at λ = 1-Operation with Highload-EGR

      Johannes Oder, Hermann Rottengruber, Christian Wouters, Marco Günther, Stefan Pischinger

      Abstract

      Gaseous fuels have a high CO₂-reduction potential and knock resistance due to their chemical and thermal properties, which make them an interesting fuel alternative for the use in modern spark-ignited engines. Within this research project the stoichiometric and homogeneous combustion process with compressed natural gas (CNG) direct injection is investigated in combination with high-load exhaust gas recirculation (EGR).

      To study the flow characteristics and mixture formation of CNG injection in a combustion chamber, experimental investigations were performed in a low-pressure injection chamber and on an optically accessible single-cylinder engine. The CNG spray investigations in the low-pressure injection chamber were performed with the aim to macroscopically characterize the natural gas jet using the Schlieren technique and planar laser-induced fluorescence (pLIF). A 3D-CFD model was created and validated with the optical single cylinder investigations and a qualitative PIV method at low-end torque and catalyst heating conditions. Both central and lateral injection positions were investigated using PIV and these results proved a good compatibility with the 3D-CFD simulations. Both the optical investigations in the low-pressure chamber and with the motored, optically accessible single-cylinder engine show that the direct natural gas injection with the side injector position has advantages compared to the central position, since the primary and secondary tumble are increased by an early and late injection timing.

      Experimental studies with the thermodynamic single-cylinder research engine show that the potential to control combustion using EGR is limited, however, an optimum combustion phasing could be maintained despite a lower combustion speed.

      The dilution capability of CNG was investigated using both EGR and excess air using two compression ratios of CR = 13 and 14.7. The investigations with excess air dilution showed the highest in-crease in indicated efficiency. The CR = 13 configuration allowed an increase of ~2.5%-points and a maximum air/fuel-ratio of λ = 1.5.

      A 0D/1D engine model was created using a predictive combustion model (SITurb) for the direct injection of natural gas and validated using measurement results. The investigations showed that low-pressure EGR cannot be used for high-load EGR with single supercharging due to reaching the com-pressor map limits. Therefore, a high-pressure EGR system was implemented.

      A Ford Eco Boost Engine was used for the engine tests and modified for CNG operation. The full-load tests at IMEP = 23 bar showed that no reduction in the cylinder peak pressure could be achieved with cooled EGR at constant center of combustion. The indicated efficiency could be slightly in-creased up to n = 4500 1/min due to the reduced wall heat losses. NO_X emissions were significantly reduced over the entire speed range from 25–62% at 5% EGR. However, HC, CH4, and CO emissions increased simultaneously by 6–26%. No knocking occurred throughout the entire full-load test at IMEP = 23 bar. A trend line comparison indicates that the results are transferable to engines with higher peak pressure limits.

      A longitudinal dynamics simulation of an RDE cycle indicated a reduction of CO₂ emissions by 22%.

   3. Novel Insight into Engine Near-Wall Flows and Wall Heat Transfer Using Direct Numerical Simulations and High-Fidelity Experiments

      Karri Keskinen, George Giannakopoulos, Michele Bolla, Jann Koch, Yuri M. Wright, Christos Frouzakis, Konstantinos Boulouchos, Marius Schmidt, Benjamin Böhm, Andreas Dreizler

      Abstract

      This study combines advanced optical diagnostics and high-fidelity Direct Numerical Simulations (DNS) to deepen the understanding of wall heat transfer processes in Otto engines under motored and fired conditions. To this end, a combination of optical diagnostics was applied simultaneously: High-resolution Particle Image Velocimetry (PIV) and Particle Tracking Velocimetry (PTV) to resolve the velocity boundary layer (BL) above the piston, Thermographic Phosphor Thermometry (TPT) to measure the wall temperature spatially resolved and Laser Induced Fluorescence (LIF) of SO₂ to track the evolution of the flame. For the complementing simulations, an entire workflow was developed that employs process calculations (GT-Power), multi-cycle scale-resolving simulations (SRSs), and DNS. Well-calibrated GT-Power models provided boundary conditions for the experimentally validated SRSs, which in turn yielded initial conditions for the DNS. Using initial conditions from the SRSs at intake valve closure, the first ever DNS of a real engine geometry was successfully performed for one motored and one fired compression/expansion stroke. It was seen that momentum and thermal BLs evolve differently: the former are affected by changes in the bulk velocity (large scale tumble motion and its breakdown), while the temperature gradients monotonically follow the increase in pressure/Reynolds number. Both the scaled momentum and thermal BLs do not exhibit a logarithmic region and the law of the wall does not hold. Several sources for deviations thereto, both in momentum and thermal BLs, are extracted. For the reactive case, it was found that the early flame kernel development is significantly affected by the strong convective flow due to tumble and only when the flame is strong enough to counter-balance the strong convection it can propagate against it. A criterion has further been developed, which allows for distinction between head-on and side-wall quenching. The vast amount of high-fidelity experimental and fully resolved numerical data generated in this project provides a comprehensive database for validation of existing computational fluid dynamics (CFD) tools and can be used for the development of improved wall heat flux models. A first attempt has been made towards this direction by developing an algebraic wall heat transfer model for LES using a data-driven approach.

5. Measurement Technology and Analysis

   1. Frontmatter

   2. Flame Luminesce in an Optically Accessible Engine with an Active Fuelled Pre-Chamber Ignition System

      Tim Russwurm, Michael Wensing, Lukas Euchner, Peter Janas

      Abstract

      Homogeneous lean or diluted combustion can significantly increase the efficiency of SI engines. Active fuelled Pre-Chamber ignition systems can overcome the problem that common spark ignitions systems are incapable to ignite strongly diluted mixtures. In the research project LEANition, an active Pre-Chamber with an integrated pressure transducer was developed. The active fuelling is done by volatile components of gasoline fuel using an in-house developed fuelling system. To understand the combustion processes with active Pre-Chamber ignition, optical investigations of the flame luminescence are performed inside an optical accessible engine through a piston crown window. To record single cycles with high temporal resolution, an highspeed intensifier and a highspeed camera was used to reach an imaging frequency of 36 kHz. The selected engine speed is 1200 rpm. Both stochiometric composition and lean charges at Lambda = 1.8 in the cylinder are investigated regarding the ignition and combustion processes. In lean cylinder environments the jets from the Pre-Chamber entrain the surrounding gas and the ignition expands from the center of the jets to the remaining cylinder. In contrast to this, at stochiometric cylinder charges, the jets cross the cylinder bore at high speed, the cylinder combustion is induced from the outside of the cylinder bore inwards to the middle of the bore. Increased charge motion in the cylinder with imposed swirl decreases the combustion duration as the flame front reaches the area between the reactive jets faster.

   3. Analyzing Pressure Pulsations in Hydraulic Systems by Merging Measurements and 3D-CFD-simulations

      Thomas A. Lenz, F. Stempfhuber, M. Spies, M. Bargende

      Abstract

      Pressure measurements in hydraulic systems and components are normally indispensable for the development and reliable operation and are mostly without alternatives. In 2017, results were presented that illustrate a relation between the measured value and the selection of the sensor including its adaptation. Deviations of more than 100% between several measurement signals were detected. Further analysis is necessary to clarify the relationships and causes.

      This article provides detailed insights into a cavitation-like fluid mechanical effect based on the influence of the sensor adaption on the pressure traces inside the damper or high-pressure chamber in hydraulic chain tensioners. Results from measurements in complete engine operation as well as experiments on an engine dummy address the difficulties in development that can arise from distorted measurement values. Previously undiscovered effects of sensor and plug on the hydraulic and mechanical behavior of the entire system are documented as well.

      In 2017, component tests provided evidence that an interaction of: I. geometry of the hydraulic component, II. system dynamics and III. volatile (local) gas content are the cause. The research from 2019 confirms this without any doubt. Based on these results, a 3D-CFD simulation was developed, which enabled an analysis of the different forms of interactions in individual system areas – both by external stimulations and by varying fluidic elasticities.

      This result could not have been achieved without the intensive exchange between the areas: developments on behalf of the customer, component tests and simulation, as this article proves.

   4. Portable HC-Tracker: Development of a Flameless Method for Mobile Hydrocarbon Measurement in Vehicle Exhaust

      Naqib Salim, Daniel Exter, Maurice Kettner, Benedikt Grob

      Zusammenfassung

      With the implementation of the Euro 6d-Temp legislation, the measurement of pollutant emissions under real driving conditions (RDE) has been put more into focus. It can be assumed that with the introduction of future emission standards, other components such as unburned hydrocarbons (HC) will be regulated. The demand for a mobile HC measurement forms the basis of this work to develop a suitable principle. In contrast to common measurement systems for determining hydrocarbon concentration such as flame ionisation detectors (FID), the presented principle works without a flame and a hydrogen supply. Through numerical simulations and experiments a prototype based on the patented novel sensor principle was developed as part of a research project. This sensor contains a temperature-controlled glow plug whose temperature is significantly lower than the flame of an FID, but which nevertheless causes ion formation in HC-containing gases, which is measurable and correlates with the HC concentration. First tests with the prototype show reproducible and HC-dependent ion currents. Based on these promising measurements, further research and development is underway to determine the potential of the sensor principle with regard to its suitability as a measurement technique for RDE.

6. Data/Security

   1. Frontmatter

   2. AI and Big Data Management for Autonomous Driving

      Frank Kraemer

      Abstract.

      Developing and testing autonomous driving (AD) systems requires the analysis and storage of more data than ever before. Clients who can deliver insights faster while managing rapid infrastructure growth will be the industry leaders. To deliver these insights faster, the underlying IT technology must support both new big data as well as traditional applications with security, reliability, and high-performance. To handle massive, unstructured data growth, the solution must scale seamlessly while matching data value to the capabilities and costs of different storage tiers and types. This whitepaper covers IBM solutions for AI workloads with a focus on IBM Storage for AI with NVIDIA DGX support.

   3. The Future Connected Car – Safely Developed Thanks to UNECE WP.29?

      Thiemo Brandt, Théo Tamisier

      Abstract

      The automotive OEMs and their suppliers are facing challenging times which are further reinforced by COVID-19. Due to technological breakthroughs and innovation such as the increasing level of automation and connectivity of the vehicles, new risks and threats arise which in the worst case may jeopardize human safety. Cyber-attacks in the automotive industry have drastically increased over the last years making Cyber Security a crucial topic. To tackle this issue, UNECE WP.29 provides a new disruptive legal framework with a tight timeline to implement. Among others, the framework addresses the implementation of a Cyber Security Management System (CSMS), a Software Update Management System (SUMS) and the Automated Lane Keeping System (ALKS). It has an impact on the organization of the OEMs and poses challenges to transform their current development and production processes and to build up the post-production activities. Dedicating resources to Cyber Security does not only have the goal to be compliant, but it can also be a differentiator. With a step-by-step pragmatic and adaptive approach, a holistic security strategy can be achieved, Cyber Security challenges appropriately met and the compliance to WP.29 ensured at acceptable costs.