Search Results

In the past application of alternative fuels was mostly concentrated to special markets - e.g. for ethanol and ethanol blends Brazil or Sweden. Now an increasing sensitivity towards dependency on crude oil significantly enhances the interest in alternative fuels. With spark ignited engines, ethanol and gasoline / ethanol blends are the most promising alternative fuels - besides CNG. The high octane number of ethanol and the resulting excellent knock performance gives significant benefits, especially with highly boosted engines. However, the evaporation characteristics of ethanol result in challenges regarding cold start and oil dilution with GDI application. This paper deals with investigations on a turbocharged DI engine operated on ethanol fuel in order to improve challenges of ethanol fuel, such as oil dilution and cold start. Cold start can be improved by injecting fuel late in the compression stroke (high pressure start) based on a refined engine design and operation strategies.

Worldwide OBD legislation has and will be tightened drastically. In the US, OBD II for PC and the introduction of HD OBD for HD vehicles in 2010 will be the next steps. Further challenges have come up with the introduction of active exhaust gas aftertreatment components to meet the lower future emission standards, especially with the implementation of combined DPF-De-NOx-systems for PC and HD engines. Following such an increase in complexity, more comprehensive algorithms and software have to be developed to cope with the legislative requirements for exhaust gas aftertreatment devices. The calibration has to assure the proper functionality of OBD under all driving situations and ambient conditions. The increased complexity can only be mastered when new and efficient tools and methodologies are applied for both algorithm design and calibration. Consequently, OBD requirements have to be taken into account right from the start of engine development.

The reduction of nitrous oxides in the exhaust gases of internal combustion engines using a urea water solution is gaining more and more importance. While maintaining the future exhaust gas emission regulations, like the Euro 6 for passenger cars and the Euro 5 for commercial vehicles, urea dosing allows the engine management to be modified to improve fuel economy as well. The system manufacturer Robert Bosch has started early to develop the necessary dosing systems for the urea water solution. More than 300.000 Units have been delivered in 2007 for heavy duty applications. Typical dosing quantities for those systems are in the range of 0.01 l/h for passenger car systems and up to 10 l/h for commercial vehicles. During the first years of development and application of urea dosing systems, instantaneous flow measuring devices were used, which were not operating fully satisfactory.

The introduction of more stringent standards for engine emissions requires continuous improvement of exhaust gas aftertreatment systems. Modern systems require a combined design and application of different aftertreatment devices. Computer simulation helps to investigate the complexity of different system layouts. This study presents an overall aftertreatment modeling framework comprising dedicated models for pipes, oxidation catalysts, wall flow particulate filters and selective catalytic converters. The model equations of all components are discussed. The individual behavior of all components is compared to experimental data. With these well calibrated models a simulation study on a DOC-DPF-SCR exhaust system is performed. The impact of pipe wall insulation on the overall NOx conversion performance is investigated during four different engine operating conditions taken from a heavy-duty drive cycle.

This paper describes the development and achievement of a target engine sound for a V6 SUV in consideration of the sound quality preferences of customers in the U.S. First, a simple definition for engine sound under acceleration was found using order arrangement, frequency balance, and linearity. These elements are the product of commonly used characteristics in conventional development and can be applied simply when setting component targets. The development focused on order arrangement as the most important of these elements, and sounds with and without integer orders were selected as target candidates. Next, subjective auditory evaluations were performed in the U.S. using digitally processed sounds and an evaluation panel comprising roughly 40 subjects. The target sound was determined after classifying the results of this evaluation using cluster analysis.

The demand for improved fuel economy and the request for Zero Emission within cities require complex powertrains with an increasing level of electrification already in a short-termed timeframe until 2025. According to general expectations the demand for Mild-Hybrid powertrains will increase significantly within a broad range of implementation through all vehicle classes as well as on electric vehicles with integrated Range Extender (RE) mainly for use in urban areas. Whereas Mild Hybrid Vehicles basically use downsized combustion engines at current technology level, vehicles with a high level of powertrain electrification allow significantly different internal combustion engine (ICE) concepts. At AVL, various engine concepts have been investigated and evaluated with respect to the key criteria for a Range Extender application. A Wankel rotary engine concept as well as an inline 2 cylinder gasoline engine turned out to be most promising.

The regulation of particle number (PN) has been introduced in the Euro 5/6 light-duty vehicle legislation, as a result of the light duty inter-laboratory exercise of the Particle Measurement Program (PMP). The heavy-duty inter-laboratory exercise investigates whether the same or a similar procedure can be applied to the heavy-duty regulation. In the heavy-duty exercise two "golden" PN systems sample simultaneously; the first from the full dilution tunnel and the second from the partial flow system. One of the targets of the exercise is to compare the PN results from the two systems. In this study we follow a different approach: We use a PMP compliant system at different positions (full flow, partial flow and tailpipe) and we compare its emissions with a "reference" system always sampling from the full flow dilution tunnel.

The DEXA Cluster consisted of three closely interlinked projects. In 2003 the DEXA Cluster concluded by demonstrating the successful development of critical technologies for Diesel exhaust particulate after-treatment, without adverse effects on NOx emissions and maintaining the fuel economy advantages of the Diesel engine well beyond the EURO IV (2000) emission standards horizon. In the present paper the most important results of the DEXA Cluster projects in the demonstration of advanced particulate control technologies, the development of a simulation toolkit for the design of diesel exhaust after-treatment systems and the development of novel particulate characterization methodologies, are presented. The motivation for the DEXA Cluster research was to increase the market competitiveness of diesel engine powertrains for passenger cars worldwide, and to accelerate the adoption of particulate control technology.

The reduction of particulate emissions limits requires new tools for the tuning of engines and exhaust aftertreatment systems. Time-resolved monitoring of low soot emissions is a key feature for such developments. The paper describes an improved photoacoustic soot sensor, and presents its applications for the characterization of transient exhaust soot emissions before and after Diesel emission after-treatment systems. The detection limit of the unit is around 5 μg/m3 soot, which is two orders of magnitude better than conventional time-resolved transmission measurement. Additionally, a wide dynamic range of four orders of magnitude can be achieved without range switching. The photoacoustic signal is proportional to the soot mass, no significant cross-sensitivities to gaseous absorbers were detected.

As emission regulations become tighter and tighter, equipment must evolve to be able to achieve the new standards. Also additional test requirements demand a system that is flexible and can accommodate differences both in the tests and the test facility. By that test cell equipment for chassis dynamometer as well as engine dynamometer applications is getting increasingly complex. That also will require new concepts for the design of such systems. In the past emission system design was more likely a collection and packaging process, which has interfaced various independent components. Now, the development of modern analytical emission systems requires a true holistic design process. This paper will describe the demands and the realization of a modern emission system. It can be shown that an extended effort during the design process will result in a high performance system, which still remains simple and robust.

The latest legislation requires a dramatic reduction of motor vehicle exhaust emission. This is also a big challenge for emission measurement instrumentation, because of almost zero concentrations of certain components in the exhaust. For current measurement devices, which are recommended by the legislation, it is almost impossible to determine such low emission levels with adequate accuracy. The paper describes a new Constant Volume Sampling (CVS) system with reduced dilution, warming and quick flow rate changing capability. Possible solutions are discussed and the properties of data measured with test facilities which are prepared to cover S-ULEV and EURO IV applications are described. Also the selection of used materials is of rising importance. The tests were performed on a dynamic engine test bed which was equipped with such a CVS system and with emission analyzing systems for raw exhaust and diluted measurements.

Emission standards as proposed in Europe and the United States for heavy duty diesel engines will require a NOx and particulate reduction of more than 90%. This cannot be achieved by internal engine measures alone. Aftertreatment systems, for either one or both emission components, plus sophisticated electronic control strategies will be required. Various strategies to comply with EU 4, 5 and US 2007 are discussed, also showing their impact on engine performance. For typical 1 and 2 liter per cylinder engines, emission reduction concepts are assessed to identify the most suitable technology for major worldwide markets. The assessment is based on thermodynamic studies, test-bed results and estimates on cost and infrastructure implications.

The paper outlines and discusses the possibilities of a new instrumentation tool for the analysis of engine and gearbox noise radiation and the prediction of pass-by noise from powertrain test cell measurements. Based on a 32 channel data acquisition board, the system is intended to be quick and easy to apply in order to support engineers during their daily work in the test cell. The pass-by prediction is a purely experimental approach with test cell recordings being weighted by measured transfer functions (from the powertrain compartment to the pass-by point).

DiMethyl Ether (DME) has been shown to be a very attractive fuel for low emission direct injection compression ignition (DICI) engines. It combines the advantages of the high efficiencies of diesel cycle engines with soot free combustion. However, its greatest drawback is the need to develop new fuel injection and handling systems. Previous approaches have been common rail type injection systems which have shown great potential in reducing harmful exhaust emissions and achieving good engine performance and efficiency due to good control of both the fuel injection characteristics and temperature. The concept also has proven benefits with respect to convenient and safe fuel handling. The logical evolution of this concept simplifies the fuel system and avoids special components for DME handling such as high pressure rail pumps while retaining all the benefits of the common rail principle.

Over the last few years there has been much interest in DiMethyl Ether (DME) as an alternative fuel for diesel cycle engines. It combines the advantages of a high cetane number with soot free combustion, which makes it eminently suitable for compression ignition engines. However, due to the fact that it is a gas under ambient conditions, it requires special fuel handling and a specially designed fuel injection system, which until recently, was not available. The use of the digital hydraulic operating system (DHOS), combined with a fuel handling system designed to cope with the properties of DME, enables the fuel to be safely and conveniently handled, In addition, the flexibility of the injection system enables injection pressures to be chosen according to the needs of the combustion.

The well-to-wheel CO2 emissions and energy use of internal combustion engines (diesel and gasoline) are compared to fuel cell automotive propulsion systems. The fuel cell technologies investigated are polymer electrolyte fuel cell (PEFC), alkaline fuel cell (AFC) and solid oxide fuel cell (SOFC). The fuels are assumed to be produced from either crude oil or natural gas. The comparison is based on driving cycle simulations of a mid-class passenger car with an inertia test weight of 1350 kg. The study shows that the optimized diesel drive train (downsized mated to an integrated starter generator) achieves the best overall energy efficiency. The lowest CO2 emissions are produced by compressed natural gas (CNG) vehicles. Fuel cell propulsion systems achieve similar or even better CO2 emission values under hot start conditions but suffer from high energy input required during warm-up.

The internal combustion engines, and the heavy duty truck diesel engines in particular, are facing a severe challenge to cope with the upcoming stringent emission legislation world-wide. To comply with these low limits, engine internal measures must be complemented with exhaust gas aftertreatment systems with sophisticated electronic control. A reduction of NOx and particulate emission of more than 90% is required. Various strategies to comply with Euro 4, 5 and US 2007 are discussed, also in view of engine performance, fuel economy and cooling system load. Recommendations are given for the most suitable approach to comply also in future with emission legislation in Europe and the United States.

In the near future the effort on the development of exhaust gas treatment systems must be increased to meet the stringent emission requirements. If the relevant physical and chemical models are available, the numerical simulation is an important tool for the design of these systems. This work presents a CFD model that allows to cover the full range of applications in this area. After a detailed presentation of the theoretical background and the modeling strategies results for the simulation of a close-coupled catalyst are shown. The presented model is also applied to the oxidation of nitrogen oxides, to a diesel particle filter and a fuel-cell reformer catalyst.