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Air spring systems gain more and more popularity in the automotive industry and with the ever growing demand for comfort nowadays they are almost inevitable. Some significant advantages over conventional steel springs are appealing for commercial vehicles as well as for the modern passenger vehicles in the luxury class. Current production air spring systems exist in combination with hydraulic shock absorbers (integrated or resolved). An alternative is to use the medium air not only as a spring but also as a damper: a so-called air spring air damper. Air spring air dampers are force elements which could be a great step for the chassis technology due to their functionality (frequency selectivity, load levelling, load independent vibration behaviour, load dependent damping). Some of their design which avoid dynamic seals by the using of rubber bellows contribute to a better ride comfort.

A fuel cell system consists of a stack, a hydrogen fuel supply and an air supply system. This provides the required air flow and pressure which allows the stack to properly react on the cathode side to recombine Oxygen with the Hydrogen's protons and electrons resulting in water and heat. In addition the air flow and pressure are supporting directly or indirectly the water management. In this paper different air supply systems for automotive application developed by NuCellSys are compared: screw compressor and electrical turbo charger. Different technologies and control strategies allow the fuel cell system integrator to find the optimum between performances, weight, volume and cost. The authors describe the challenges and the new frontier of air supply systems for automotive fuel cell system application.

Rising oil prices and increasing strict emission legislation force vehicle manufacturers to reduce fuel consumption of future vehicles. In order to meet this target, the process of converting fuel into useable energy and the use of this energy by the different energy-consuming vehicle's subsystems have to be examined. Vehicles' subsystems consist of energy-supplying, energy-consuming, and in some cases energy-storing components. Due to the high complexity of these systems and their interaction, optimization of their energy efficiency is a challenging task. By introducing individual operational strategies for each subsystem, it is possible to increase the energy efficiency for a specific function. To further improve the vehicle's overall energy efficiency, holistic control strategies are introduced that distribute the energy between the subsystems intelligently.

Due to the diversity of Heavy Duty Vehicles (HDV), the European CO2 and fuel consumption monitoring methodology for HDVs will be based on a combination of component testing and vehicle simulation. In this context, one of the key input parameters that need to be accurately defined for achieving a representative and accurate fuel consumption simulation is the vehicle's aerodynamic drag. A highly repeatable, accurate and sensitive measurement methodology was needed, in order to capture small differences in the aerodynamic characteristics of different vehicle bodies. A measurement methodology is proposed which is based on constant speed measurements on a test track, the use of torque measurement systems and wind speed measurement. In order to support the development and evaluation of the proposed approach, a series of experiments were conducted on 2 different trucks, a Daimler 40 ton truck with a semi-trailer and a DAF 18 ton rigid truck.

Securing the desired strength and durability characteristics of suspension components is one of the most important topics in the development of commercial vehicles because these components undergo multiaxial variable amplitude loading. Leaf springs are essential for the suspension systems of trucks and they are considered as security relevant components in the product development phase. In order to guide the engineers in the design and testing department, a simulation method is developed as explained by Bakir et al. in a recently published SAE paper [1]. The main aim of the present study is to illustrate the validation of this simulation method for the durability of leaf springs based on the results from testing and measurements. In order to verify this CAE Method, the calculated stresses on the leaf springs are compared with the results of strain gage measurements and the fatigue failures of leaf springs are correlated with the calculated damage values.

The driving comfort influences the customer purchase decision; hence it is an important aspect for the vehicle development. To better quantify the comfort level and reduce the experiment costs in the development process, the subjective comfort assessment by test drivers is nowadays more and more replaced by the objective comfort evaluation. Hereby the vibration comfort is described by scalar objective characteristic parameters that correlate with the subjective assessments. The correlation analysis requires the assessments and measurements at different vehicle vibration. To determine the objective parameters regarding the powertrain excitations, most experiments in the previous studies were carried out in several test vehicles with different powertrain units.

The objective of the presented research is to analyze the cause-and-effect chain of the emergence of tire marks and to indentify how the intensity of a friction-related tire mark on asphalt or concrete pavements can provide additional information related to forces or slips at the marking wheels. Focusing on tire marks due to abrasive wear, the influences on the intensity of tire marks are analyzed based on three categories: vehicle dynamic parameters, tire and road properties, which determine the sensitivity of tire marking for a specific tire-road combination for constant vehicle dynamic parameters; and optical parameters, influencing the contrast of a given tire mark. The analysis includes a new objective method for the assessment of the tire mark intensities derived by photos of tire marks, generated with a tire measurement trailer. Additionally a test rig was developed to determine the tire marking sensitivity with reference marks under controlled friction conditions.

Lubricant oil derived ash deposits still represent a major issue in diesel particulate filter operation in vehicles. In literature various ash deposition patterns are described. The two boundary deposition patterns are (a) wall layer and (b) filling at the back end of the inlet channels. The patterns are often associated with different regeneration methods. Continuous regeneration is supposed to result in a homogeneous ash layer, whereas periodic (active) regeneration is reported to result in back end filling. The current contribution describes the basic mechanisms associated with ash transport phenomena in particle filters. On the basis of (a) frequency of ash exposure to flow (b) ash particle structure re-entrainment and finally (c) axial ash transport the different deposition pattern can be explained. Exposure to flow accomplished by periodical soot removal, either by passive or active regeneration is the first step.

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.

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.

Downsizing and direct injection in modern DISI engines can lead to fuel impinging on the cylinder walls. The interaction of liquid fuel and engine oil due to fuel impinging on the cylinder wall causes problems in both lubrication and combustion. To analyze this issue with temporal and spatial resolution, we developed a laser-induced fluorescence (LIF) system for simultaneous kHz-rate imaging of fuel and oil films on the cylinder wall. Engine oil was doped with traces of the laser dye pyrromethene 567, which fluoresces red after excitation by 532 nm laser radiation. Simultaneously, the liquid fuel was visualized by UV fluorescence of an aromatic “tracer” in a non-fluorescent surrogate fuel excited at 266 nm. Two combinations of fuel and tracer were investigated, iso-octane and toluene as well as a multi-component surrogate and anisole. The fluorescence from oil and fuel was spectrally separated and detected by two cameras.

The TOP TIERTM Diesel fuel standard was first established in 2017 to promote better fuel quality in marketplace to address the needs of diesel engines. It provides an automotive recommended fuel specification to be used in tandem with regional diesel fuel specifications or regulations. This fuel standard was developed by TOP TIERTM Diesel Original Equipment Manufacturer (OEM) sponsors made up of representatives of diesel auto and engine manufacturers. This performance specification developed after two years of discussions with various stakeholders such as individual OEMs, members of Truck and Engine Manufacturers Association (EMA), fuel additive companies, as well as fuel producers and marketers. This paper reviews the major aspects of the development of the TOP TIERTM Diesel program including implementation and market adoption challenges.

This paper makes a contribution toward a more efficient chassis durability process for the development of passenger cars, in which the simulation of relevant load data is a time-consuming part. This is especially due to the full vehicle model complexity which is usually determined by the demands of rough road simulations. However, for the load calculation on a racetrack, time saving model approaches that are more simplified might be sufficient. Our investigation comprises two levels of vehicle model complexity: one with all chassis parts modeled in a multibody system environment and one characteristic curve based model in an internal simulation environment. Both approaches consider an original chassis control system as a Software-in-the-Loop model. By the evaluation of real-world experiments the main influence factors in terms of durability are demonstrated. With the help of those highly sensitive durability criteria the measurement and simulation results are then compared.

The overall efficiency of hybrid electric vehicles largely depends on the design and application of its energy management system (EMS). Despite the load coordination when operating the system in a hybrid mode, the EMS accounts for state changes between the different driving modes. Whether a transition between pure electric driving and internal combustion engine (ICE) powered driving is beneficial depends, among others, on the respective operation point, the route ahead as well as on the energetic expense for the engine start itself. The latter results from a complex interaction of the powertrain components and has a tremendous impact on the efficiency and quality of EMSs. Optimization based methods such as dynamic programming serve as benchmark for the design process of rule based control strategies. In case no energetic expenses are assigned to a state change, the resulting EMS suffers from being sub-optimal regarding the fuel consumption.

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.

The reduction of fuel consumption as well as the rising demands of customers regarding a vehicle’s driving dynamic and the legislator’s continually rising demands are a current issue in vehicle development. Hybrid vehicles offer a possibility to rise to this challenge. Realistic driving cycles are of utmost importance for the calibration of a hybrid vehicle’s operational strategy. Deriving replacement speed cycles from extensive customer data sets seems to be an approach for solving these problems. The contribution at hand describes the derivation of replacement cycles by using stochastic models, probabilistic (weighted) drawings and a combinatorial optimisation. The novelty value is that the characteristic influences of all drivers are being considered in the generation due to the stochastic modelling.

Since the last decade, alternative powertrains are playing an important role in the strategy of car manufacturers. One important goal is the introduction of zero emission powertrains. These powertrain systems raise increasing political and public interest with the hydrogen fuel cell engine being the most competitive powertrain technology. During the development of this new technology, all the functional aspects including the automotive vehicle safety need to be considered. Hydrogen sensors are installed in the system to optimize the performance of a hydrogen fuel cell system and to enhance the safety concept. New results of sensor optimization and innovative test and development methods based on real vehicle data are described in this paper.

This paper presents the application to full vehicle finite element simulation of a steady state rolling tire/wheel/cavity finite element model developed in previous work and validated at the subsystem level. Its originality consists in presenting validation results not only for a wheel on a test bench, but for a full vehicle on the road. The excitation is based on measured road data. Two methods are considered: enforced displacement on the patch centerline and enforced displacement on a 2D patch mesh. Finally the importance of taking the rotation of the tire into account is highlighted. Numerical results and test track measurements are compared in the 20-300 Hz frequency range showing good agreement for wheel hub vibration as well as for acoustic pressure at the occupant’s ears.

In the field of heavy-duty applications almost all engines apply the compression ignition principle, spark ignition is used only in the niche of CNG engines. The main reason for this is the high efficiency advantage of diesel engines over SI engines. Beside this drawback SI engines have some favorable properties like lower weight, simple exhaust gas aftertreatment in case of stoichiometric operation, high robustness, simple packaging and lower costs. The main objective of this fundamental research was to evaluate the limits of a SI engine for heavy-duty applications. Considering heavy-duty SI engines fuel consumption under full load conditions has a high impact on CO₂ emissions. Therefore, downsizing is not a promising approach to improve fuel consumption and consequently the focus of this work lies on the enhancement of thermal efficiency in the complete engine map, intensively considering knocking issues.

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.